If you actually look closely enough, it's so painfully and blatantly obvious that all East Romance (including Romanian and Aromanian) uniquely developed together as the same language way after Latin was a thing, and yes, probably south of the Danube. There's a direct correspondence or correlation between the vast majority of the inherited Latin lexicon if you compare them, and many are not found in other Romance or have unusual, unique senses that developed the same in them and apart from all others. Here are just a few examples of many hundreds (there is a lot more vocabulary shared between them, close to 2000 words, but I just wanted to share some of the ones with the unique/unusual developments not shared by the rest). For verbs, both the full infinitive with resulting nounal form, and the first person singular is listed, since Aromanian no longer has the standard infinitive, for better direct comparison:
Ro. bătrân - Ar. bitrãn / bitãrnu, meaning "old, aged (of a person)", from Latin 'veteranus' (all the other Romance languages either didn't inherit this term or use it to mean literally a veteran)
Ro. zbura(re) / zbor - Ar. azbuirari / azboair, meaning "to fly" from Vulgar Latin '*exvolare, exvolo' (another pretty unique construction and phonetic development in East Romance, with some equivalents found in some Italian dialects/languages)
Ro. dezmierda(re) / dezmierd - Ar. diznjirdari / diznjerdu, meaning "to caress, fondle", from Vulgar Latin *'dismerdare, dismerdo' (meaning "to remove feces", from 'merda', but with a very unique development from the idea of wiping an infant's bottom becoming "caring for", not found in other languages)
Ro. fecior - Ar. ficior, Megl. Rom. fitšor meaning "boy, youth, young man", from Vulgar Latin '*fetiolus' (only found in Balkan Romance), diminutive of 'fetus'
Ro. biserică - Ar. bãsearicã, Megl. Rom. bisearică, meaning “church”, from Lat. ‘basilica’ (most western Romance standard languages words for church developed rather from ‘ecclesia’ instead)
Ro. apă - Ar. apã, meaning "water", from Latin 'aqua' (the only Romance descendants with this -p-, although some Sardinian dialects have 'abba')
Ro. lume - Ar. lumi, meaning "the world, humanity, people collectively", from Latin 'lumen' (which actually meant "light", showcasing another unique development in East Romance, probably from the idea of "the light of life" figuratively)
Ro. pământ - Ar. pimintu, meaning "ground, earth, soil" from Latin 'pavimentum' (instead meaning a type of floor or pavement)
Ro. dimineață - Ar. dimineatsã, meaning “morning”, from a Vulg Lat. *’de-manitia’, from ‘de mane’ (“early in the morning”; this construction is not found outside Balkan Romance)
Ro. zi(uă) - Ar. dzuã, meaning “day”, from Latin ‘dies’
Ro. Dumnezeu - Ar. Dumnidzã, meaning "God", from Latin 'Domine Deus' (only these East Romance languages use this as the default/main word for God, versus just 'Deus' in others, although a similar construction is found in some other western languages in certain usages like Italian 'domineddio' and French 'damedieu', meaning "God Almighty")
Ro. zână - Ar. dzãnã, meaning "fairy", from Latin 'Diana', the name of a pagan goddess (also found in Albanian as 'zanë' and a few minority western Romance languages, like Asturian 'xana')
Ro. drac - Ar. drac, meaning "devil", from Latin 'draco' (which actually meant "dragon", and was the sense taken by all the other Romance)
Ro. coacin - Ar. coatsin, both referring to “a reddish/brownish color on the head of sheep”, from Latin ‘coccinus’, from Greek (these clearly developed a very specific sense apart from other Romance due to the shepherding lifestyles of the Vlachs)
Ro. noaten - Ar. noatin, meaning “yearling (one-year old) lambs”, from Latin ‘annotinus’ (which meant “of last year”, showcasing again a narrowing of a general concept to a specific shepherd one)
Ro. puțin - Ar. putsãn, meaning “little, few”, uncertain but probably a VulgLat ‘*paucinus’ or ‘*putinus’, from alteration of ‘pittinus’ or ‘putilus’ (not found in any other Romance languages)
Ro. cântec - Ar. cãntic, meaning "song", from Latin 'canticum' (also found in Albanian as 'këngë', most western Romance rather use derivatives of Lat. 'cantio, cantione' for "song")
Ro. deștepta(re) / deștept - Ar. dishtiptari / dishteptu, meaning "wake up", of uncertain exact origin, possibly a Vulgar Latin *'de-excitare' or more likely 'despectare', meaning "discern, perceive" (this also led to the word for "smart/intelligent" in Romanian, deștept; but this formation isn't found in other Romance, and may have been influenced by 'aspectare', whence 'aștepta' - "to wait")
Ro. cufuri(re) /cufuresc - Ar. cufuriri / cufurescu, meaning "to have diarrhea", from Latin 'conforio' + '-esco' (not found in other Romance)
Ro. urdina(re) / urdin - Ar. urdinari / urdin, also meaning "have diarhhea" but also "to trot around in a circle or the same area over and over", from Latin 'ordinare, ordino' (clearly a unique sense development within Eastern Romance not shared with others, where the word kept closer to the original meaning)
Ro. codobatură - Ar. coadã-baturã / cudubaturã, meaning "wagtail", from Vulgar Latin *'codabattula' (some similar constructions with the elements reversed also found in a few western Romance languages or dialects)
Ro. codru - Ar. codru, meaning "woods, forest", from Vulgar Latin '*codrum/*quodrum', from 'quadrum' (both mean forest but come from the Latin word for square, with the meaning likely coming from a square patch of woods; also related to Albanian 'kodër' "hill")
Ro. pădure - Ar. pãdure, also meaning "woods, forest", from Vulgar Latin 'padule', from 'paludem', which actually meant swamp (this original sense is the one found in all other non Eastern Romance descendants)
Ro. albină - Ar. alghinã, meaning "bee", from a Vulgar Latin *'alvina' supposedly meaning "beehive"; this word is not found in other major Romance languages, possibly in some North Italian dialects with a slightly different meaning
Ro. răbda(re) / rabd - Ar. arãvdari / aravdu, meaning "to endure", possibly from a Vulgar Latin *'reemendare' or '*rigidare', but not found in any other Romance
Ro. spăla(re) / spăl - Ar. aspilari / aspel, meaning "to wash", from a Vulgar Latin *'experlavare, experlavo' (mostly unique to East Romance, possibly along with a few southern Italian dialects and Albanian 'shpëlaj')
Ro. învăța(re) / învăț - Ar. nvitsari / nvets, meaning "to learn", from Vulgar Latin '*invitiare, invitio' meaning “accustom, habituate, familiarize”, from 'vitium', meaning "vice" (this has a specific semantic development different from the other languages)
Ro. aprinde(re) / aprind - Ar. aprindiri / aprindu, meaning “to light, turn on”, from Lat. ‘apprehendere, apprehendo’ (in western Romance this took on the meaning of “to learn”)
Ro. pleca(re) / plec - Ar. plicari / plec, meaning “to leave”, from Latin ‘plicare, plico’ (meaning “to fold”, and with unique E. Romance semantic development, the opposite of Iberian, like Spanish ‘llegar’ “to arrive”, while Italian ‘piegare’ maintained the original sense of “to fold”)
Ro. apuca(re) / apuc - Ar. apucari / apuc, meaning “grab”, possibly from VL. ‘*aucupare’ or ‘occupare’
Ro. cutremura(re) / cutremur - Ar. cutrimburari / cutreambur, meaning "to shake, quake" from Vulgar Latin *'contremulare, contremulo' (again specifically an East Romance construction)
Ro. fi(re) / sunt, fiu, Ar. hiri / hiu, meaning "to be", from Latin 'fio', meaning "become". (related to this you have the formations in Ro. 'ființă' and Ar. 'hiintsã', both meaning "creature" or "being")
Ro. viață - Ar. yeatsã, meaning "life", probably derived from 'viu' / 'yiu' ("alive") or a Vulgar Latin *'vivitia'. Related, you have Ro. 'învia / înviere / înviez' and Ar. 'anyeari / anyedz', meaning "revive, resurrect, come to life" from a V. Lat. '*invivare' with the suffix *-idio' (-ez/-edz).
Ro. drept - Ar. dreptu / ndreptu, meaning "straight" or "right", from Latin 'directus', although a common Romance word, it displays the same shift of -ct to -pt not found in other Romance; compare also Ro. noapte and Ar. noapti (“night”), from Latin ‘noctis’
Ro. lemn - Ar. lemnu, meaning “wood”, from Latin ‘lignus’ (of course found in all Romance but shows the unique development of Latin -gn- to -mn- in East Romance)
Ro. adânc - Ar. adãncu, meaning “deep”, from Latin ‘aduncus’ (which meant “hooked” instead, and this was not inherited by western Romance, only borrowed later)
Ro. miel - Ar. njel, meaning "lamb" from Lat. agnellus (turned out differently than western Romance cognates). There is also the related Ro. mioară and Ar. njioarã, diminutives meaning little lamb.
Ro. mijloc - Ar. njilgioc, Megl. mejluc meaning "middle", from Lat. 'medius locus'
Ro. jumătate / jumate - Ar. giumãtati / giumati, meaning "half", from a VL. '*diemitatem', from metathesis of 'medietatem' ("meaning center, midpoint")
Ro. anțărț - Ar. antserts, meaning "two years ago", from Lat. 'anno tertio' (formation uniquely Balkan Romance)
Ro. rușine - Ar. arushini, meaning "shame", probably from some Vulgar Latin derivation of 'roseus', meaning "red" (whence Ro. roșu and Ar. aroshu)
Ro. arunca(re) / arunc - Ar. arucari / aruc, probably from a Vulgar Latin *'eruncare, erunco' from 'runcus' (not found in other Romance varieties)
Ro. ridica(re) / ridic - Megleno-Romanian ardicare / rădic, meaning "to raise", probably from Latin 'eradicare' (meaning "root out" or "eradicate", another unique semantic development in East Romance)
Ro. sufruncea(ua) - Ar. sufrãmtseauã, meaning "eyebrow" (although archaic in Romanian), from Vulg. Lat. '*subfronticella' (not found in other Romance)
Ro. sprânceană - Ar. sprindzeanã, also meaning "eyebrow", probably a Vulgar Latin '*supergenna' as a variation of 'supercilia' (this formation is unique to East Romance although similar to some others found in West Romance)
Ro. geană - Ar. dzeanã, meaning "eyelash", from Latin 'gena' (meaning "cheek" and not inherited in any other languages)
Ro. însura(re) / însor - Ar. nsurari / nsor, meaning "to marry/wed", from Vulgar Latin *'inuxorare, inuxoro' from 'uxor' "wife" (not found in other Romance except perhaps Neapolitan)
Ro. bărbat - Ar. bãrbat, Megl. Rom. bărbat, meaning "man", from Latin 'barbatus' (meaning "bearded"; only eastern Romance developed this into a noun meaning "man" rather than adjective meaning "bearded")
Ro. petrece(re) / petrec - Ar. pitreatsiri / pitrec, meaning "to spend or pass the time", from V. Latin '*pertraicere, pertraicio'
Ro. întuneca(re) / întunec - Ar. ntunicari / ntunic, meaning "to darken", from Vulgar Latin '*intunicare' (which meant "to cover with a tunic" a unique development only in East Romance).
Ro. întuneric - Ar. ntunearic meaning "dark", probably from Latin 'tenebricus'
Ro. îmbăta(re) / îmbăt - Ar. mbitari / mbet, Megleno-Rom. ămbet, meaning "get drunk" from Vulgar Latin '*imbibitare, imbibito' (not found in other Romance)
Ro. greață - Ar. greatsã, meaning “nausea” figuratively but in Ar. also literally “burden”, from a VL. ‘grevitia’ (“weight, heaviness”), from grevis < gravis “heavy” (unique local formation not found in other Romance); related, you have both Ro. and Ar. ‘greu’, meaning “heavy”
Ro. rezema(re) / reazem - Ar. arãdzãmari / aradzim, meaning “to support”, possibly from VL. ‘*rhizomare’, from Greek, or ‘remediare’ (not found in other Romance)
Ro. scutec - Ar. scutic, meaning "diaper", of uncertain origin, possibly Latin 'scutica' ("leather lash or whip") or alternatively of Slavic origin
Ro. mătură - Ar. meturã, meaning "broom", possibly an early South Slavic borrowing from 'metla' or a Vulgar Latin *'mattula', diminutive of 'matta' ("mat of rushes")
Ro. plimba(re) / plimb / preumbla - Ar. priimnari / priimnu, meaning "to walk, stroll", from Lat. 'perambulare, perambulo' (only preserved in East Romance)
Ro. pătrunde(re) / pătrund - Ar. pitrundiri / pitrundu, meaning "pierce, penetrate, perforate", from Latin 'pertundere, pertundo' (mostly East Romance, also found in Sardinian)
Ro. fereca(re) / ferec - Ar. fãricari / fãric, meaning in Ro. "to hoop, fetter, chain, or strengthen by adding metal" and Ar. "to shoe a horse", probably from Latin 'fabricare, fabrico' (a unique development of this word) or alternatively a Vulgar Latin '*ferricare' from 'ferrum', meaning "iron"
Ro. lepăda(re) / lepăd - Ar. alipidari / aleapid, meaning "to drop, throw away, cast, renounce", probably from Latin 'lapidare' (meaning "throw stones" surviving as inherited only in East Romance)
Ro. frământa(re) / frământ - Ar. frimintari / frimintu, meaning "to knead (dough)", probably from Latin 'fermentare, fermento' (only inherited in East Romance)
Ro. refeca(re) / refec - Ar. aruficare / arufec, meaning "to hem, hemstitch", uncertain but possibly from Latin 'refricare'
Ro. înfășa(re) / înfaș - Ar. nfãshari / nfash, meaning “to swaddle”, from Vulgar Latin *’infasciare, infascio’, from ‘fascia’ (“strip, ribbon or band”)
Ro. tânăr - Ar. tinir, meaning "young", from Vulgar Latin *'tenerus' from 'tener' (which meant "soft, delicate, tender or youthful", a meaning that developed differently in other Romance languages)
Ro. cal - Ar. cal, meaning “horse”, from Late Latin ‘caballus’ (the other Romance languages did not contract this word to the extent that East Romance did, like Italian ‘cavallo’; but see also Albanian ‘kalë’); related you have terms like Ro. călare - Ar. cãlar, meaning “astride, mounted”, and Ro. călăreț - Ar. cãlãrets “horseman”
Ro. munte - Ar. munti, meaning “mountain”, from Latin ‘mons, montis’ (most western Romance uses ‘montania’)
Ro. toamnă - Ar. toamnã, meaning "autumn", from Vulg Latin *'autumna' (rather than the standard masculine 'autumnus' that the other western Romance derived from, like Spanish ‘otoño’, Italian ‘autunno’)
Ro. iarnă - Ar. earnã, meaning "winter", from Vulgar Latin *'hiberna' (similarly feminine unlike the standard 'hibernus' that developed in the others, or taken from its plural instead, like Spanish ‘invierno’, Italian ‘inverno’, and French ‘hiver’)
Ro. mormânt - Ar. murmintu, meaning "tomb", from Latin 'monumentum' (most other languages developed it to mean "monument")
Ro. sarcină - Ar. sartsinã, meaning “pack, burden, obligation”, from Lat. ‘sarcina’ (mostly preserved in E. Romance), and derivatives Ro. însărcina - Ar. nsãrtsinedz “to burden”
Ro. moară - Ar. moarã, meaning “mill”, from Latin ‘mola’ (most western Romance uses descendants of ‘molinus’ for mill and ‘mola’ for the millstone or grindstone specifically)
Ro. fluier - Ar. fluiarã, meaning "flute", possibly from a Latin 'flaturalis' (uniquely East Romance and probably borrowed by Albanian as flojere)
Ro. veșted - Ar. veashtid, meaning "withered, faded”, from VLat ‘*vescidus’, from ‘vescus’ or ‘viscidus’ (only inherited in E. Romance)
Ro. înalt - Ar. naltu / ãnaltu, meaning "high/tall", from Latin 'altum' (but unlike other Romance, they prefix it with in-)
Ro. bucium - Ar. bucium, in Ro. meaning "horn or trumpet" but also "tree stump or trunk" as in Ar. (which lost the other sense), from Latin 'bucinum' (which meant "trumpet")
Ro. vrea / vrere / vreau - Ar. vreari / voi, meaning "to want", from Latin 'volere, vol(e)o' (Romanian has a variant conjugation with 'voi' as the first person singular like Aromanian, with different usage, but replaced the standard form with 'vreau' through analogy with the infinitive; both these verbs have the past partiple vrut or vrutã)
Ro. curcubeu - Ar. curcubeu, meaning "rainbow", from Latin 'circus bibit' (meaning "ring that drinks", mostly East Romance, similar formations in some minority West Romance dialects)
Ro. smulge(re) / smulg - Ar. zmuldziri / zmulgu, meaning "to snatch, pull away, tear away", from Lat. 'exmulgere/ exmulgo' from 'ex-' + 'mulgere' ("to milk")
Ro. sâmbătă - Ar. sãmbãtã, meaning "Saturday", from Latin '*sabbata' from 'sabbatum' (although possibly influenced by Slavic later; unlike most western Romance equivalents, they have the nasal infix -m-)
Ro. sărbătoare - Ar. sãrbãtoari, meaning "holiday", also in Ro. "celebration", from V Lat. '*servatoria', from 'servare'
Ro. surpa(re) / surp - Ar. surpari / surpu, meaning "to annihilate, destroy, crumble, vaniquish", from Vulg Lat '*subrupare' from 'rupes' (meaning "cliff")
Ro. scărpina(re) / scarpin - Ar. scãrchinari / scarchin, meaning “to scratch, scrape”, from Late Latin ‘scarpinare’
Ro. spânzura(re) / spânzur - Ar. aspindzurari / aspindzur, meaning "to hang (execute someone)", from Vuglar Latin '*expendiolare' (not found in most other Romance, possibly in Italian 'spenzolare' but this doesn't have the connotation of hanging to kill someone)
Ro. vătăma(re) / vatăm - Ar. vãtãmari / vatãm, Megl Rom. vatăm meaning “to kill”, from Latin ‘victimare’ (only preserved in Balkan Romance)
Ro. broască - Ar. broascã, meaning "frog" (but in Ar. also tortoise/turtle), from a Vulgar Latin *'brosca', probably from Greek (also found in Albanian breshkë; in Romanian the compound broască țestoasă means "turtle/tortoise", the later element being related to Latin testudo)
Ro. râie - Ar. arãnji, meaning "scabies, itch, mange", from Latin 'aranea' (which actually meant "spiderweb", again showing unique development in East Romance, due to the appearance of the skin diseases being compared to the look of a web; although it's possible that Galician raña also shares this sense)
Ro. beli(re) / belesc - Ar. biliri / bilescu, meaning "to skin", prob from Lat. 'vellere' with a change of conjugation
Ro. merge(re) / merg - Ar. neardziri / nergu, meaning "to go", from Latin 'mergere, mergo' (which meant instead "to immerse, dip, plunge, merge")
Ro. linge(re) / ling - Ar. alindziri / alingu, meaning “to lick” from Latin ‘lingere, lingo’ (mostly East Romance and some Italian languages like Friulian; most western Romance derives from a probable Germanic term, like Italian 'leccare')
Ro. femeie - Ar. fumelj / fumealji, in Ro. meaning "woman" and in Ar. meaning "child, or family", from Lat. familia (in archaic Romanian it used to also mean "family" but this sense is now obsolete; see also Albanian fëmijë, "child")
Ro. cireșar - Ar. cirishar, meaning "the month of June" (now a nonstandard regional folk term in Ro.), derived from cireașă / cireashã which means "cherry" or from a Vulgar Latin '*ceresiarius'
Ro. alunar - Ar. alunar, both being alternative folk terms for “July”, from the words ‘alună / alunã’ (which means “nut”, from Lat. ‘abellona’)
Ro. Sânmedru - Ar. Sãnmedru, meaning "October" (folk name for the month), from Latin 'Sanctus Demetrius', whose holiday is in October
Ro. brumar - Ar. brumar, alternative folk names for “November”, from brumă / brumã, meaning “frost”, from Latin ‘bruma’. Other folk names for November are Ro. iezmăciune and Ar. ayizmãciuni, with the first element of Greek origin.
Ro. andrea / undrea / îndrea - Ar. andreu, meaning "December" (again a folk term in modern Ro., but also meaning "knitting needle" due to the custom of knitting socks on St. Andrew's day), from Latin 'Andreas' (the saint whose feast day is Nov 30)
Ro. cheag - Ar. cljag, meaning "clot", from Vulg Lat 'clagum', from 'coagulum' (the metathesis of the Latin word is only found in East Romance)
Ro. burete - Ar. bureati, meaning both "sponge" and "a type of mushroom" in Ro. but just "mushroom" in Ar., from Latin 'boletis' (a type of mushroom)
Ro. bocet - Ar. boatsit, meaning "wail, cry", from VLat. 'vocitum', from 'vox', or "voice" (unique to E. Romance). Related, from a VL. *'vocire', you have Ro. boci(re) / bocesc and Ar. butsiri / butsescu, meaning "to bemoan, lament". There is also archaic Ro. 'boace' and Ar. 'boatsi', meaning "voice" (in modren Romanian this was replaced by the neologism 'voce')
Ro. acolo - Ar. aclo, meaning "there, over there", from VLat. 'eccu(m) illoc' (this particular construction not found outside E. Rom)