This is likely the reason it started. The priest caste had all things and said don’t touch my cow rounding fuck. Cow becomes scared because low iq inbreds assume that the priests say don’t touch it must be holy. So all things that come from this now holy beast becomes holy. Low iq idiots can’t have the cow so they take what the priests don’t (milk goes to the priests). So they are left with shit and piss.

And here we are.

I just made that up, it it is likely the most plausible reason. Priests never said anything because they don’t fuck with their cow. They just collect shit and piss. So they let the deletes do what that do. Yeah I know it’s spelled different.

They do that in the more retarded areas of Africa as well (most of them)

And you would be wrong...

Yes, many Hindus, particularly in rural India, cover their doorsteps and floors with cow dung for ritual purification, aesthetic decoration, and practical utility. 

Ritual Purification: During festivals like Diwali and Govardhan Puja, women apply a paste of cow dung to the doorstep to purify the space, invite the goddess Lakshmi (prosperity), and protect the home from negative forces.  The dung is viewed as sacred and a symbol of purity rather than dirt.
Cultural Significance: In Sanatan Dharma, the cow is considered divine (often referred to as Kamadhenu), and its byproducts are believed to possess therapeutic and antiseptic properties.  Sculpting cow dung into representations of Mount Govardhan is a specific ritual honoring Lord Krishna. 
Practical Use: Beyond religion, cow dung paste is used as a natural coolant for floors in hot climates, acts as a pest repellent against insects and mosquitoes, and serves as a binding agent that prevents dust from rising.