Map of pre-1945 distribution of Ainu languages and dialects.
Coastline adapted from OpenStreetMap
Sources:

Fukazawa, Mika. Hokkaido Ainu Dialects: Variation from the Perspective of the Geographical Distribution of Vocabulary (2018)[1]Lee, Sean. Evolution of the Ainu Language in Space and Time[2][3]National Museum of Japan. Map of Traditional Ainu Settlement Areas[4]Shibatani, Masayoshi. The Languages of Japan(1990)[5]
Own work
Noahedits