The Maratha clan system is a very complex one. Maratha Shahannav Kuli and has 96 clans. The Maratha caste is the largest caste in India and they also dominate a lot of political and social decisions made since times immemorial. They are also very rigid -- which is why Virat said his family is 'kaafi' traditional. The progeny of the clan is of utmost importance to the inflexible Marathas because they seek the 'Assal' (real Maratha blood )
It is actually not the highest caste but a middle cast comprising of warriors, farmers, ironmen etc. They began by being Kunbis who served Mughals. However, with time they prospered and even became rulers. Chavan (pronounced as Chav-van and not Chauhan) are Kshatriyas and one of the 96 Maratha clan and have been traditionally military men for kings and later the country. That also explains the wealth that the Chavan family has -- it could be ancestral
Joshis are Brahmins which is actually the higher caste but Maratha kings were superior in power and Brahmins were generally appointed as advisors to kings. But historically the Marathas have a wrath against Brahmins which had denied education to the community when the Varna system was in place.
So in the scene where Virat catches Mane snooping and says, 'Main Maratha hi Nahi, Mavla hoon'. Chhatrapati Shivaji Maharaj is worshipped by them.
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