What is the main topic of the map?

Key Features:

• Title: ЗАПАДНАЯ СИБИРЬ (Western Siberia)
• Geographic coordinates are marked, including the Arctic Circle (Северный полярный круг), and lines of latitude (70°, 60°, 50°).
• Lines of longitude are also indicated (60°, 70°, 80°, 90°, 100°).
• A section is labeled "Условные знаки" (Conventional symbols), suggesting a legend is present or intended.
• Rivers and bodies of water are depicted.
• The map appears to be part of an educational resource, likely for geography studies.