The peoples of northeastern Siberia are very interesting ethnically and culturally, and also quite diverse. The Chukchi, Koryak, Yupik (Siberian Inuit), Kamchadal live along the coast. They are Paleo-siberians and each group has their own language (though the Kamchadal language is almost extinct, many Kamchadal have intermarried with Slavic Russians). These peoples, especially the Yupik, are related to the Eskimos (Inuit) of North America.
Further inland are Tungusic tribes such as the Evenki, Lamuts,Oroch, etc. who are related to the Manchus of China.
Also inland are the Yakuts (Sakhha) who are Turanian, and who may be distantly related to the Kazakhs and Kyrgyz. The Yakuts are the most numerous of these peoples, therefore perhaps having the best chance of preserving their native language.
There is also an inland people called the Yukaghirs who are thought to be possibly Turanian in origin but who speak a language not closely related to any other.