Despite its 3,000-kilometres coastline, few people see Vietnam as a maritime country. Here Li Tana presents a powerful new argument about Vietnamese history: that key political changes resulted from the impact, economic and otherwise, of the sea. This is a finely layered account covering the two millennia before colonisation that radically restructures how we understand the role of the maritime and trans-regional in Vietnam’s early history. Drawing on exhaustive research of Chinese, Vietnamese, and Japanese sources, Li reveals that it is only when viewed against the background of the sea that Vietnam’s past can be properly understood. In contrast to traditional perceptions of an inward-looking society dominated by Chinese cultural influence, Vietnam was shaped by dynamic littoral economic and cultural contact.