Why is Russian literature considered part of Western culture when so much of Russia is in the East?

Question

Russia is a country that straddles both the East and West, and is culturally very diverse.

Why and how did so much of Russian literature become part of the Western Canon?

To put it another way, why are Tolstoy, Chekhov and Dostoyevsky considered part of Western literary culture or part of the Western canon?

Is it because of the themes of Russian literature or because of some historical event or just because of geography or something else?

For context the following definitions apply:

Russian Literature = refers to the literature of Russia and its émigrés and to Russian-language literature.
Western Culture / Canon = refers to the book by Harold Bloom entitled "The Western Canon: The Books and School of the Ages". Please review that book if further clarification is needed.
culture = the arts and other manifestations of human intellectual achievement regarded collectively.
West / East = refers to west of the Ural Mountains / east of the Ural Mountains until you hit the International Date Line.

Answer 1

The reason may be that all famous Russian writers I can think of (Tolstoi, Dostoyevsky, Chekhov, Pasternak, Gogol) came from or lived in the European part of Russia, e.g. in or near Moscow or St. Petersburg, which have always been considered as European cities, and of course were strongly influenced by European culture.

All writers that live in the Asian part of Russia are certainly a part of Asian literature. I cannot think of any famous name, though.

Answer 2

I don't see how the Ural boundary may be seriously considered. It is not about geography, but rather about the continuity of tradition.

The Western culture is built around three axes: Hellenism, Christianity, and Renaissance. One may accept them, or rebel against them, but all of them are central to the very way of Western thinking.

All educated Russians were educated this way. That makes Russia a part of the Western tradition, and Russian literature the part of the Western Canon. They were thinking on same problems French and German did, and approached them within the same discourse. I don't know any Russian writer who'd take, say, Islamic (or Buddhist, Confucian, Shinto, Bharat...) point of view.