First Baltic text is recorded in 14th century, and you are speaking about some Baltic language..
So, what is the issue there? Are you arguing, that Baltic languages did not exist before 14th century because of writing? Well, so were most of modern languages, who had their writing established only by 18th century - it is not news.
No one argues, that there are a lot of finnish genes in modern baltic people, as there was a massive influx of finnish people and quite a lot of them were assimilated into Baltic people. Most of that influx happened after 6th AD, so Baltic people of 6th AD had a lot less N1c than now, however most modern south slavic people probably had none R1a and also did not used slavic language, unlike baltic who used baltic, when they branched off PIE.
I have no problems regarding finnish part, as I believe in only one solution(and that is not gas camera - I'm not that evil) for them on my quest to reunite baltic with slavic, as this stupid russian evilmongery and lie distribution business has to stop and if it ends with russian dissolution, as they are doing now with belorussians(which is also part of my heritage), then why would I care? That is my fairytale, after all - who really cares, if that is your nightmare, if you act as indians, who have problems accepting, that India was invaded by people from steppes of Europe and which also created caste system as a result. Well - segregation is not good, but neither is extermination of locals, what some IE tribes practiced towards early noneuropean looking Uralic people, for example.
As for wiki - it says exactly, that I mentioned, that there are no slavic language prior 6th century. And we can only argue about language here - nothing else. if you don't like your own sources or actually don't understand them - just don't use them. No one forces you to do so.
Before Zarubnitsy culture was Milograd culture(it is souther orange), which was baltic:
Listen, wiki does not say that Zarubintsy culture was slavic or even proto slavic. It says, that it is
connected to proto-slavic. From what I understand it is still baltic, just as Milogrady culture is baltic. Let me explain how it is
connected to proto-slavic.
Zarubnitsy culture is connected to Kiev culture, as Kiev culture is descendant of Zarubnitsy culture(maybe, possibly).
https://en.wikipedia.org/wiki/Kiev_culture
English wiki says, that: "It is widely considered to be the first identifiable
Slavic archaeological culture"
According to wiki rules, this is very bad text, as widely in russian wiki version translates 4+ versus 2(and I mentioned before - science is not a democracy - either those 4+ are dead wrong or 2 and I would not put my money on most scientists, that they are right):
"В вопросе этнической принадлежности носителей киевской культуры нет единства мнений. В. Н. Даниленко, П. Н. Третьяков,
В. Д. Баран, Р. В. Терпиловский и ряд других исследователей относят её к
славянам[3], предполагая, что на основе киевской возникают последующие славянские культуры раннего средневековья:
пеньковская и
колочинская.
В. В. Седов и И. П. Русанова считают её
балтской[4]. При этом Седов рассматривает славянство колочинской культуры как результат взаимодействия с пеньковской, а киевскую культуру как субстрат для пеньковской и колочинской культур. "
So, NO - we
can't still consider Kiev culture as slavic - not in my dreams or even nightmares. Choose what you want.
I will use map for later
connected cultures:
Kievan culture branches into two:
1.
Kolochinskaya culture, which is related to penkovka culture, though it countains also baltic, so it is not real culture, but mix in process. I sure would not call them slavic and neither you or anyone else.
2.
Penkovka culture or as we know about them from history - as
antes. Yellow on this map. This is the culture, where it is identified as slavic people and I would agree, and we would end this discussion with some result. However, this is what russian wiki says about antes(both sources seems like very recent - 2012, which means, that they also are more trueful, than older unprecise sources):
1. Специалист по археологии древних славян
И. П. Русанова отрицала славянскую атрибутацию пеньковской культуры, поскольку пеньковские древности совершенно не похожи на памятники достоверно славянской пражско-корчакской культуры. По её мнению местное население носящее название «анты» возможно уже с VI в. говорило на славянском языке, но сохраняло еще свои этнографические особенности, а в VII веке уже полностью растворилось в славянской среде
[10].
(Possibly, that nonslavic antes, who wildly differ from venedi(which are considered really slavic culture) spoke in slavic language from 6th AD already, but were different from slavic and by 7th AD were fully dissolved in slavic environment)
2. По мнению кандидата исторических наук Алексахи А. Г. эта точка зрения подтверждается на основании критерия бездиалектности славянского языка, из которого следует, что никакая археологическая культура, синхронная пражской, не может быть славянской. По его мнению анты были западными балтами, но были ассимилированы славянами лишь в VI веке
[11][12].
(It says, that on the basis of
nondialectial nature of slavic language no archeological culture, that is sinchronous with
Prague-Korchak Culture can be slavic. He has an opinion, that antes were western baltic, that were assimilated by slavic only in 6th century).
So, what it follows, is that we can for sure say, that only Prague-Korchak culture(in map it is orange Venedi) was slavic(
https://en.wikipedia.org/wiki/Prague-Korchak_culture) and rest were baltic, who were assimilated by slavs.
Here is the thing about Prague culture. It is late 5th century(most probably all the other cultures on this map also have the same dates) - more like 6th century culture and it collerates with proto-slavic ideas hypothesis. But from what I read in wiki, name of Veneds most certainly point to prussian Baltic origin(even in lithuanian name of water of vanduo), and if that is true, that more likelly means, that originally veneds were baltic as it is unlikely, that slavs might have tribe name of nonslavic origin, as their own and had venedi bay in southern shores of Baltic sea, as all the bays in the area were baltic up to invasion of Germans, who were employed by Bohemian king Ottokar I. Linguisticaly it makes more sense that slavic have much more linguistical similarities with prussians, than rest of baltic, because rest of baltic encountered slavs much later. Prague culture was also influenced by goths and when they left it did not need to migrate to become slavic. Quite possibly, that proto-slavs are very late development of gothidfied prussians, as I have read before that prussian people could talk and understand each other - also people who were considered slavic, it is only currently hard to understand why, because we do not have live prussian language to compare and live venedians as well for that matter. Also, if we take into account, that prussians had words, that sound very slavic to rest of baltic, slavic might be just dialect of prussians which developed even more differences after visit of goths. I only claimed that eastern slavs are balts so far, but with
venedo prussian branch as proto-slavs, slavic languge is baltic as well.
Very f*cked up baltic language, but still - it is baltic.
https://ru.wikipedia.org/wiki/Этногенез_славян_по_данным_археологии
This is the list of approved cultures, as slavic:
Корчакская •
Пражская •
Суковско-дзедзицкая (лехитская) •
Ипотешти-кындештская •
Волынцевская •
Роменско-борщёвская •
Новгородских сопок •
Рюсенская (сербо-лужицкая) •
Лука-райковецкая •
Фельдбергская •
Карантанская
Related, but still - under question(which actualy means - should not be considered as slavic, but these are cultures, that are identified as the ones, that participated in ethnogenesis of slavs):
Чернолесская •
Милоградская •
Поморская •
Подклёшевых погребений •
Пшеворская •
Зарубинецкая •
Почепская •
Киевская •
Черняховская •
Колочинская •
Пеньковская •
Именьковская •
Браслетообразных сомкнутых височных колец •
Псковских длинных курганов •
Смоленско-полоцких длинных курганов
I APOLOGISE IF YOU DO NOT UNDERSTAND CYRILIC AND RUSSIAN, BUT READING WIKIPEDIA IN ENGLISH DOES NOT REALLY GIVE YOU MUCH KNOWLEDGE ABOUT SLAVIC TOPIC. Despite not being russian, I do read russian and actually my only source about baltic are in russian, and I trust them when they come out with sensational breakthroughs, as much of the history are lies, that includes any slavic sources, that were redacted couple of times, just like Bible. Spread of slavic languages truly bloomed only in 9th century, after "work" of Cyril and Methodius.
Something similar happened to Livonia, where lettish language was used as liturgical language in southern part of Livonia and made into demise at least two finnish tribes: livonian and south estonians in modern Latvia, not to mentioning that there were settled captured votians and other people(even russians) who dissolved into latvians.
TL;TR You can search for other solutions for the rest of your life, but you will come to this eventually: Proto-slavic language is prussian branch, which developed with the help of goths.