Which portions of World History are important for UPSC Mains?

Focus on events from the 18th century onwards, specifically the Industrial Revolution, World Wars, and the Unification of Germany and Italy.
Prioritise thematic understanding of ideologies like Socialism, Capitalism, and Communism, alongside the process of Decolonisation in Asia and Africa.
Use Arjun Dev’s NCERT to analyze the "why" and "how" of these shifts and their global socio-economic impacts rather than memorizing military dates.