Which reason made it difficult for the caste segregated patterns of social interaction to survive?

Urbanisation

The development activity of the state and the growth of private industry also affected caste indirectly through the speeding up and intensification of economic change. Modern industry created all kinds of new jobs for which there were no caste rules. Urbanisation and the conditions of collective living in the cities made it difficult for the caste-segregated patterns of social interaction to survive.