First of all, let's talk numbers: There are 21 Ethnic Republics in the Russian Federation, From Kalmykia to Tatarstan to Chuvashia. And there are more than150 Ethnic groups within the Federation's expansive borders, including such tiny ethnicities as Aguls, Kola Lapps, and Wakhs.
Many of these ethnicities are tiny, numbering less than 50,000 souls, but others are far more significant. Tatars, for example, have played key roles in Russian history, and the capitol of Tatarstan, Kazan, is a major center of Muslim culture inside Russia. Chechens, as well, have had a historically troubled relationship, first with the Russian Empire, then with the Soviet Union, and now with the Russian Federation. In ethnically mixed Dagestan alone there are an alleged 70 different ethnicities, including Aguls, Avars, Dargins, Kumyks, Laks, Lezgins, Nogais, Rutuls, Tabasarans, and Tsakhurs. And Kalymkia, with its tiny capitol of Elista, is the only Bhuddist European nation—a land of steppe on the western coast of the Caspian Sea. Some of these ethnic republics have a majority of their titular ethnicity—such as Tuva, Chechnya, and Kalmykia, while others, like Udmurtia and Khakassia, are dominated by Russians and other minorities.
These peoples, whose territories were taken over first by the aggressively expanding state of Muscovy and then later by the Russian Empire, provide modern Russia with a rich and varied patchwork of diversity, but that diversity may seem, to the outsider, far less initially apparent than the diversity of, say, the United States. This is due to a number of factors, many of them resoundingly negative. There were enormous efforts under the Soviet Union to repress or eliminate ethnic languages, and to "Russify" the children of ethnic minorities by forcing them into Russian-language schools. There were also widespread efforts to Russify the written languages of minority peoples, forcing them to publish books in modified versions of the Cyrillic alphabet and altering traditional names to conform to the Russian system.
Though the Soviet Union, at least initially, played lip-service to recognizing ethnic groups and encouraging their self and "class-consciousness," this proceeded with parallel collectivization and forced assimilation which broke traditional ties to the land and extended family and clan units. Additionally, superior Russian political power caused many to deny their ethnic origins and claim a false Russian identity. Some ethnicities, especially those in Central Asia, fled across the borders of the Soviet Union, leading to large populations of Azerbaijanis and Turkmen in Iran, as well asTajiks, Turkmen and Uzbeks in Afghanistan.
Some ethnicities faced wholesale deportation under the Stalin years. Chechens and Kalmyks are major examples of this treatment: both ethnicities were loaded wholesale into cattle cars as "enemies of the people" and did not see their native lands for years to come (those who returned at all). But many have simply been quietly assimilated into Russian culture, their numbers too small to be noticed by the world at large.
Following the breakup of the Soviet Union, there were independence movements of varying strength in many of the Ethnic republics--most notably Tatarstan, Chechnya (resulting in a major war) Yashkuts and Bashkyrs. However, the establishment of ethnic republics has also allowed them to establish official languages as well as their own constitutions.
Russia remains to this day an ethnically diverse country, with some ethnicities, most notably the Kalmyks, Tuvans, and Tatars, laying serious claim to their ethnic heritages and working to repair damaged connections with their past, as any trip to one of the major ethnic republics, which should be included on any Russian itinerary, will demonstrate.