Udayadityavarman I (1001 - 1002 A.D.) & Jayaviravarman (1002 - 1010 A.D.)
When Jayavarman V passed away in 1000 A.D., the historical account of his royal family disappeared with the emergence of the new king named Udayadityavarman I, who became the king through violent conflict. He ruled only for a few years before being ousted and killed in 1002. This was followed by the struggle of power of the two princes, Jayaviravarman and Suryavarman I. The former prince ascended the supreme throne in 1002, but his regime was consistently challenged by his rival Suryavarman I, who successfully overthrew king in 1010. During this decade of civil war, no significant monument was built.
Suryavarman I (1010 - 1050 A.D.)
His reign was rather long but not very smooth, and Suryavarman I spent much of his time and energy to defend his kingship. He was the first king who built his palace surrounded by the wall in order to fortify himself from being attacked and this palace was situated in the vicinity of later Angkor Thom. Suryavarman I proclaimed to be the descendant of Brahmin Kaundinya and princess Soma. Later in 1022 A.D, Suryavarman I expanded his territory to the West up to the Lopburi in modern Thailand. The major construction built by this king was the Preah Vihear on the Dangrek Mountain and the Phimeanakas, a modest temple with pyramidal style located near his palace. Suryavarman I also started to build the second Angkor's reservoir, the West Baray which is almost twice as large as the East Baray.
Udayadityavarman II (1050 - 1066 A.D.)
Mounting to the supreme throne after the death of his predecessor, Udayadityavarman II ruled over the Angkor Kingdom without peace. He was not the son of Suryavarman I, but a descendant from the different lineage of Yasovarman I's spouse. The stone inscription during his reign praised one of his faithful general Sangrama who quell several major rebellions for the king. Udayadityavarman II built the renowned Baphoun Temple devoted to god Shiva, however, it appeared that some stone sculptures were also dedicated to Lord Buddha. This king completed the construction of the West Baray started since the time of his former king, and built the West Mebon, a raise-earthen island, in the center of it. A temple dedicated to god Vishnu was constructed on the island, but now had long been vanished. The West Baray is still in use today.
Harshavarman III (1066 - 1080 A.D.)
Following the death of Udayadityavarman II, the new king Harshavarman III who was the former king's older brother, mounted the throne. No monument built by this king was known and there was very few historical account referred to this king, who was believed to die in a violent rebellion.
Jayavarman VI (1080 - 1107 A.D.)
Ascending the throne in 1080 A.D., Jayavarman VI did not seem to have any direct connection with the royal family of the preceding kings. Probably he was from the different maternal sub-lineage, which was too far to entitle his right to the crown. The center of his ancestors' power was more or less to the West of the Angkor in the area of Phimai, now in Thailand. Jayavarman VI claimed to be the descendents of legendary Kambu and Mera, which was different from his immediate predecessors. This could imply that he succeeded the throne through violent conflict.
During his reign, there was rarely any monument built, except the one at the center of his power - the Phimai temple.
Dharanindravarman I (1107 - 1113 A.D.)
Jayavarman VI died in 1107, and the throne was followed by his elder brother Dharanindravarman I. This king was less ambitious as well as less energetic. He was ousted and killed in a civil war which lasted for only one day by his nephew who later became one of the greatest king of the Angkor, Suryavarman II.
Suryavarman II (1113 - 1150 A.D.)
Upon rising to power, Suryavarman II was a highly ambitious Khmer king. He was the great builder of the most impressive temple of Khmer, the Angkor Wat which is one of the World's Wonders with its magnificent architecture. Angkor Wat is a mountain temple dedicated to god Vishnu with five towers linked by galleries to signify the heavenly residence of Hindu gods. It is 65 meters high and the outer rectangular enclosure mesuring 1.5 km by 1.3 km which is surrounded by moat of 200 meters wide. In addition to its remarkable size, Angkor Wat also houses thousands of sculptures and stone carvings which amplify the delicacy of Khmer artworks. It took 37 years to complete the construction of this temple with over 50,000 workforce.
Apart from being a great royal builder, Suryavarman II was also a great warrior. He sacked several Champa states to the east and even waged an unsuccessful war with the strong Ly Dynasty of Vietnam. To the west, he conquered the Haripunjaya Kingdom, one of the Mon tribal states in central Thailand, and extended his power to as far north to the southern border of modern Laos and as far south to the border of Grahi Kingdom in Malay Peninsula which was around the present-day Nakorn Sithammarat, a southern province of modern Thailand. His territory expanded up to the border of the Pagan kingdom (ancient Burma) in the West.
Other monuments, in addition to Angkor wat, built during the reign of Suryavarman II are Beng Melea, Banteay Samre, Chey Say Tevoda, Thommanon.
Minor Reigns (1150 - 1181 A.D.)
Surprisingly the final destiny of this great king still remains in mystery. The last inscription referring to Suryavarman II was carved in 1145 A.D. with his preparation to invade Vietnam and probably he died sometime between 1145 and 1150 in a battlefield.
The death of Suryavarman II led to the decline of the Angkor Empire for a short interval and the successive kings were rather weak as well as tyrannical. The reign was followed by Dharanindravarman II (1150 - 1160 A.D.), Yasovarman II (1160 - 1165 A.D.), and Tribhuvanadityavarman (1165 - 1181 A.D.), respectively. Yasovarman II siezed the power from Dharanindravarman II, and in turn, was ousted by Tribhuvanadityavarman.
In 1177, a Champa King, who was the bitter enemy of the Khmer, attacked the Angkor by sailing his troops up along the Mekong River. A fierce naval battle was fought on the Great Lake of Tonle Sap and resulted in the painful defeat of the Angkor which subsequently fell into the hand of the Champa. The current Khmer king Tribhuvandityavarman was under the subjugation of the Champa until 1181.