For the pre-colonial era(before 1511)Since it is often underlooked, are there any good accessible resources you recommend? Anything from books to documentaries to museums will do. TLDR: title
Try "A History of Early Southeast Asia: Maritime Trade and Societal Development, 100–1500" Though as the title suggests, it focused on the Trade and Social aspects of SEA. maybe /u/PangeranDipanagara could give more
What time period are you interested in?