Proto-Baltic (PB, PBl, Common Baltic) is the unattested, reconstructed ancestral proto-language of all Baltic languages. It is not attested in writing, but has been partly reconstructed through the comparative method by gathering the collected data on attested Baltic and other Indo-European languages. It represents the common Baltic speech that approximately was spoken between the 3rd millennium BC and ca. 5th century BC, after which it began dividing into Western and Eastern Baltic languages. Proto-Baltic is thought to have been a fusional language and is associated with the Corded Ware and Trzciniec cultures. Baltic languages share some common features with Slavic languages, suggesting the possibility of an earlier linguistic unity in development. Generally, Proto-Baltic had a SOV word order. Proto-Baltic is said to have possessed certain unique traits, such as free accentuation with two pitch accents, turning short Proto-Indo-European vowels *o, *a into *a, retaining and further developing the Proto-Indo-European ablaut, retaining *m before dental consonants and the productivity of the word stem ē. Also, the proto-language is thought to have had its own set of diminutive suffixes, identical endings for verb tenses and moods, past tense by applying thematic vowels *-ā- and *-ē-, as well as its own lexicon, including onomastic elements. Proto-Baltic area Baltic hydronyms cover a vast area of 860,000 km2 from Vystula River in the west to Moscow in the east and from the Baltic Sea in the north all the way to Kyiv in the south. The current Lithuanian and Latvian lands combined constitute approximately one-sixth of the former Baltic territory. Some researchers suggest that in the past Baltic lands from Vystula to Daugava were inhabited by Baltic Finnic tribes but they were assimilated by the Baltic newcomers later on. There is still an ongoing debate regarding the boundary of hydronyms in the southwest: Lithuanian linguist Simas Karaliūnas believed that practically all of the basins of Oder and Vystula Rivers belonged to the Baltic hydronym habitat while German linguist Hermann Schall suggested that Baltic hydronyms could be found much further west all the way to Elbe, Saxony and Rügen island. During the 2nd and 1st millennium BC, the Baltic people inhabited larger territories than Germanic and Slavic people did at the time. It is estimated that the Proto-Baltic lands had up to 500,000 people. Inhabitants of the Proto-Baltic area were surrounded by Germanic people in the west, Slavs in the south and Finno-Ugric people in the