Indianisation refers to the spread of Indian languages, culture, cuisines, diaspora, and the impact.
Since India is a big country, it has different languages and cultures. The spreading of Indian culture started in the first century in the southeast region. The expansion of Indian culture into these areas was termed "Indianisation". The term was coined by French archaeologist, 'George Coedes'
There are many theories on how this expansion of Indian culture started. Each theory focuses on different castes of Indians as the main source of propagation.
These theories are:
-Theory of Vaishya traders
-Theory of the Kshatriya warriors
-Theory of Brahmins