The Dark Ages of Cambodia covers the history of Cambodia from the fifteenth to the nineteenth century, a period of continued decline and territorial loss. Cambodia enjoyed a brief period of prosperity during the sixteenth century because its kings, who built their capitals in the region southeast of the Tonlé Sap along the Mekong River, promoted trade with other parts of Asia. This was the period when Spanish and Portuguese adventurers and missionaries first visited the country. But the Siamese conquest of the new capital at Longvek in 1594 marked a downturn in the country's fortunes and Cambodia became a pawn in power struggles between its two increasingly powerful neighbors, Siam and Vietnam.