The fifteenth to the nineteenth century was 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 Tonle 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 Thai conquest of the new capital at Lovek 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. Vietnam's settlement of the Mekong Delta led to its annexation of that area at the end of the seventeenth century. Cambodia thereby lost some of its richest territory and was cut off from the sea. Such foreign encroachments continued through the first half of the nineteenth century because Vietnam was determined to absorb Khmer land and to force the inhabitants to accept Vietnamese culture.
