“…In mainland north-eastern Siberia, archaeological obsidian is common in the Chukotka and Kamchatka regions, due to the close proximity of primary sources, particularly in the latter territory (Dikov 1997; Kuzmin et al . 2008; Kiryak 2010; Grebennikov & Kuzmin 2017). Farther west and south-west, the frequency of obsidian artefacts decreases significantly in, for example, the basins of the Kolyma and the Indighirka Rivers, and along the Okhotsk Sea coast (see Kuzmin et al 2018).…”