What mostly Hindu area is not part of India?

The mostly Hindu area that is not part of India is the country of Nepal. Nepal is an independent nation situated north of India in the Himalayan region. It is known for its ancient history, cultural heritage, and as the home to the world's highest peak, Mount Everest. The majority of Nepal's population follows Hinduism, and it was the only official Hindu nation in the world until it became a secular state following the declaration of the interim constitution in 2007.

Extra: Hinduism is one of the oldest religions in the world, with a rich tapestry of gods, goddesses, rituals, and philosophies. Although predominantly practiced in India, Hinduism has spread to other parts of South Asia and around the globe due to migration and the Indian diaspora. It is a religion that encompasses a wide variety of practices, beliefs, and rituals, with the flexibility to accommodate a diverse range of spiritual experiences and gods.

In the context of Nepal, Hinduism has shaped much of the country’s cultural and religious life. Major festivals like Dashain and Tihar (similar to Diwali in India) are widely celebrated. The living goddess tradition, or Kumari, is also unique to Nepal, specifically in the Kathmandu Valley.

Even though Nepal is now officially a secular state, Hinduism still forms a significant part of its national identity. It's important to note that the concept of secularism in South Asia can be different from the Western model, often aiming to provide equal respect and opportunity to all religions rather than completely separating religion from the state.