In these four volumes, now published in paperback, twenty-one scholars of international reputation consider the whole of mainland and island Southeast Asia from Burma to Indonesia. Volume 1 charts Southeast Asia's beginnings, from prehistory to c. 1500. Accounts are given of Southeast Asia's early development, based on archaeological and anthropological evidence; the establishment of kingdoms such as Sri Vijaya, Champa, Angkor, Pagan, and of the Vietnamese state; and the period's economic history, religions and popular beliefs.
Nicholas Tarling was Professor of History at the University of Auckland from 1968 until 1997 and a Fellow of its New Zealand Asia Institute. He was the editor of The Cambridge History of Southeast Asia and wrote nearly 50 books and a large number of articles on the region.
Knowing next to nothing about SE Asia, it's nice to find an all-encompassing, layman-type volume that gives you a nice entry-level understanding of the area. This volume, doubly so, because the authors, in general, make an attempt to free the study of the region from stupid generalizations and archetypes of scholars who have to jargonize and po-mo the crap out of everything. Here, you get the region treated as it is, largely on its own terms. Broken up into three sections (history, economics, and religion), there's a lot of overlap and flip-backing needed, but it isn't a detriment. A further division looks at mainlaind, peninsular SE Asia and the maritime bits through separate if interlocking divisions, too. Surprisingly, the section on economics is pretty awesome, not as plodding and dense as economic histories tend to be, while the section on religion was abstruse and difficult, with little to no context or explanation of what the hell Saivism might be, or the various schools of Buddhism.
Perhaps the most reliable and simple source for people who know absolutely nothing about Southeast Asia. It very extensively explains the contrast between the maritime and the mainland regions. The section on religion is my favourite. This book is strictly academic, however, and the writing is extremely dry for recreational reading.
This is a four part volume on Southeast Asia and this volumes covers the prehistorical era to 1500, on the cusp of Portugese settlement in Malaka. This is the best treatment of early Southeast Asia but it might be a bit dated. The sections on archaeology are now fairly old.
As fascinating as early Southeast Asia is, the written record is very small except for Vietnam. So for Angkor and Pagan, there are few tantalizing nuggets of information about how the people lived.
I would definitely recommend this as basic reading for understanding Southeast Asia.