Indian culture was introduced to the local people there through the Sastras, Epics and Puranas which attracted them.
This was perhaps the contribution of the Brahmins. Then came the Indian merchants who initially occupied the coastland but later moved into the hinterland. The Chinese text of the 5th century AD states that in Fu-nan there were 500 familities of merchants from India.
The question of analysing the Indian influence in Malaysia has engaged the attentioin of French, Dutch and British scholars for nearly a century. Their findings show that there were four sources of Indian influence: (1) the Amaravati (2nd and 3rd centuries AD.) (2) the Gupta (4th to 6th century AD) (3) the Pallava (6th to 8th century AD.) and (4) Bengal (8th to 10th century AD).
The first was not very influential anywhere outside India except Ceylon. The Gupta influence tool the small Amaravati influence in its stride and finally eclipsed it. Thus effectively there were only three waves of cultural influences in South East Asia.