Thank you! These people are neither Chukchi nor Yakuti. Chukchi live in Chukotka and Yakuti are in Yakutia. On Sakhalin there are a few small natinalities of idigenous people. One of them is hivkhi, the other one ines and I don't remember the other one. But the common name for all of them is gilyaks. Though it is better not prounounce this name in the presense of one of them, as it may offend a person, as in one of the indigenous languages it means "dogs"... This is the story...
I love this series, first time I see what a reindeer REALLY looks like! Are these people Tchukchi? of Yakuts? Best regards, congratulations on great phot work you're doing!