MtDNA haplogroup L is the oldest maternal branch of humanity comprises almost all the lineages in sub-Saharan Africa. All Eurasian haplogroups descend from L3, the subclade that is the most common in the Arabian peninsula and North-East Africa. All four top branches of L (L0, L1, L2 and L3) are nevertheless found in North Africa, the Middle East and Europe.
Haplogroup L is actually present at trace frequency (0.2 to 0.5%) in most of Eastern and Central Europe, and is only totally absent in Finland, Baltic countries, Croatia, Slovenia, Austria, and North-East Italy, and the Caucasus (except among the Ossetians and Nogays). This actually correlates well with the distribution of E-V13, which means that when the E-V13 population reached Europe, only about 1% of the women who accompanied them belonged to mtDNA L. In contrast, in Iberia and France, the percentage of mtDNA L women accompanying E-M81 men would have been between 20 and 40% (U6 would have been another major lineage).
It is interesting how Cantabria and Auvergne both have unusually elevated percentages of both E-M81 and R1a-SRY1532 (the Mesolithic variant) and both have a higher percentage of mtDNA L, U4, U5 and V than their neighbours.
The L lineages in Central Italy were surely brought by the Etruscans from Anatolia. Additional lineages may have come to Rome during the imperial period.
The slightly higher percentage (0.5%) of L in Serbia and Bosnia corresponds to a known hotspot of Y-haplogroup T (a lineage closely linked to E1b1b).