What four culture regions make up the Russian heartland?

It's not quite accurate to say there are "four culture regions" that make up the Russian heartland. The concept of a "Russian heartland" is somewhat fluid and depends on the criteria used to define it.

However, we can identify four major cultural and historical regions that are often considered part of the Russian heartland, based on their historical significance, cultural influence, and geographic location:

1. Central Russia: This region encompasses Moscow, the capital, and the surrounding areas. It's the most densely populated region, home to major industrial centers and cultural institutions, and it has historically been the political, economic, and cultural center of Russia.

2. The Volga Region: This area extends along the Volga River, a vital waterway for trade and transportation. It's diverse in terms of culture and ethnicity, with a mix of Slavic, Turkic, and Finno-Ugric influences.

3. The Urals: This mountainous region acts as a natural barrier between Europe and Asia, and it's rich in mineral resources. It's home to a unique culture, influenced by both European and Asian traditions.

4. Siberia: This vast region stretches across northern Asia and encompasses diverse landscapes and ethnicities. Historically, it was a frontier region for Russia, and its vast resources have been crucial for the country's development.

It's important to remember that these regions are not monolithic in terms of culture. Each one contains further subdivisions, ethnic groups, and regional identities that contribute to the complex cultural tapestry of the Russian heartland.