Yellow = the area of continuous Slavic population after early expansion.
As seen on the map, East Galindian became totally
surrounded by Slavic tribes and therefore it got assimilated.
The Eastern Galindians is an extinct East Baltic tribe, which from the 4th century lived in the basin of the Protva River, near the modern Russian towns of Mozhaysk, Vereya, and Borovsk.
The Russian chronicles first mention Eastern Galindians as Goliadj in 1058. It's likely that they were not completely assimilated by Russians until the 15th (or 16th) century.