The Bronze Age
The history of Estonia between 1800 BC and 501 BC
The beginning of the Bronze Age in Estonia is dated to approximately 1800 BC. The development of the borders between the Finnic peoples and the Balts was under way. The first fortified settlements, Asva and Ridala on the island of Saaremaa and Iru in the Northern Estonia began to be built. The development of shipbuilding facilitated the spread of bronze. Changes took place in burial customs, a new type of burial ground spread from Germanic to Estonian areas, stone cist graves and cremation burials became increasingly common aside a small number of boat-shaped stone graves.
About 7th century BC, a big meteorite hit Saaremaa island and created the Kaali craters. About 325 BC, the Greek explorer Pytheas possibly visited Estonia. The Thule island he described has been identified as Saaremaa by Lennart Meri, though this identification is not widely considered probable, as Saaremaa lies far south of the Arctic Circle.
Reference: Wikipedia