It is very possible that it is the first time you hear about the Champa Kingdom, and that for a simple reason: it has ceased to exist centuries ago, absorbed by the Vietnamese definitely in 1720 (although its power has been almost extinct since its defeat at the hands of the same Vietnamese in 1471). Before that, it had remained more or less independant despite regular fights against its immediate neighbors Cambodia and Vietnam, and the great influence exerced by the two great powers of the continent, China, and in the distance, India.
The Origins: the first mention of the Kingdom of Champa date back to 192 AD in Chinese scriptures, where it appears under the name Lin-Yi. It is probably at that time that the 'Kingdom' was founded, in the region of today's Hue, it seems as a result of the revolt of a local official against Chinese authority. One wants to be careful when using the term of 'Kingdom' or 'State' when talking about Champa. The Chams were of Malayo-Polynesian origin, and therefore their form of government must have been close to those traditionally found among those people: several small groups, scattered all along the coast that provided many small enclaves. Some leaders, more powerful than the others will ascertain their authority over the whole of the Chams
The Early Years: what happened during the first centuries is still quite unclear to us, as all the written evidence comes from Chinese sources, and thus, necessarily biased. What we do know is that it was a period of constant struggle between the Lin-yi and Chinese, the intesity of which depended on the strength of the dynastic Power in China. It is also a time during which the frontiers fluctuate greatly, notably the northern one between the Lin-yi and Tongkin, a Chinese territory.
Cultural developments: for several reasons, as the Tang dynasty arrived in power (7th century) the aggressions of the Chams against the Chinese provinces to the north ceased for 2 centuries, and the kings even send missions to China. It is the time that saw great developments in the arts and architecture. Beautiful monuments were built, most of them revealing the strong influence of the Indian culture, both on the aesthetics and the religion (several of these buildings were dedicated to Vishnu. Moreover, from the middle of the 8th century, the cult of the Linga, the symbolic form of Shiva, is supperposed to the traditional cults).
Years of unrest: the second half of the 8th century will be a very important period in Champa's history. The political center shifts to the south, a new dynasty starts, and at the same time, the Chinese begin to refer to the Chams as Huan-Wang instead of Lin-Yi. It's also a new period of unrest, as they are attacked repeatedly by the Javanese, who will end up destroying at least two temples. These attacks will eventually cease, and at the begginig of the 9th century, it's Champa that starts a series of offensives against China to the north, and Cambodia.
Indravarman II: in 854 comes to power Indravarman II. His accession to power is very important in several ascpects. It is a renewal of the years of peace and friendship with China Champa had known more than a century earlier, but also the start of good relations with Java (exchanges with that region will result in a marked Javanese influence on Cham arts from the 10th century onwards). He is the founder of the 6th dynasty and the capital shifts again to the north, as a new capital city is built, Indrapura. Finally, this dynasty will show an unprecedented attention to the religion and their duties. Mahayana Buddhism is introduced.
Vietnam enters the stage: but the tide changes, and for good, against Champa during the 10th century. As a consequence of the fall of the T'ang dynasty. the Vietnamese succeeded in creating the independant kingdom of Dai-co-Viet. At first, no problem arised between Champa and the new state. But in 979, at the demand of a refugee from that very country, the Cham King sent a float against its capital that was partially destroyed in a storm. The next year, he sent the messenger from Lo Hoan, who had just seized the throane of Dai-co-Viet for himeself, in prison. He died in the attack that resulted from that foolish gesture, and Indrapura was destroyed. The next king, Indravarman IV, had to flee to the south; the north ended up in the hands of a vietnamese who proclaimed himself king of Champa when Indravarman died in 988. In the meantime, the calls for help from the Chams directed at China had no effect.
Losses: it is the founder of the 7th dynasty, Harivarman II, who reconquered the north, and the capital was again Indrapura. But what is important here, is that this will be the first in a long series of attacks and counter-attacks, usually all lost by the Chams. Early in the 11th century, the north was definitely lost at the hands of the Vietnamese, who even took a little later the new capital further south, Vijaya. The next Chams kings tried to rekindle hope by maintaining good relations with both China and Angkor, but no real help ever came from either front. After a last, and disastrous Cham counter-attack in 1068, the whole north of Champa is officially abandoned to the Vietnamese.
Champa and the Khmers: until the middle of the 13th century, the relations between the two neighbors will be mostly peaceful; this situation was mostly due to the fact that now Cham had also to face the attacks of the Khmers to the West. When that exterior threat was finally warned off, local rebellions broke. This pattern of fights first against the Khmers, then against local rebels will be repeated again later during the 12th century, until in 1203, Champa fell under the Khmer domination. However, despite the fact that the Chams were without a king of their own to lead them, the last one having fled by sea, the Khmers evacuated Champa after only 17 years. The reason for this withdrawal remains unknown to us even today.
The relations with the Mongols: Champa was, in 1220, when it was finally free of the Khmer occupation, exhausted. The reconstruction could only be slow and difficult. Moreover, Champa was still considering the reconquest of its lost territories to the Vietnamese. As soon as 1225, only 5 years after having recovered their independance, the Chams started raids against the Vietnamese, which ultimately led to new attacks from both sides. The Chams resisted fiercely, and their ennemies finally agreed to a peace arrangement, since their northern border was under threat of the Mongols. From the moment they took over the power in China, they demanded that southern countries payed the same respect to them that they had paid to the Chinese emperors, and the kings of Champa, Cambodia and Annam where supposed to meet with their chief, Kublai Khan, to pay their respect personaly. When they did not comply, Mongols troops were sent but they failed to win, and finally were forced to withdraw, Khan having already too many front to cover and the king of Cham having sent him presents to appease him.
A fatal mistake: the peace lasted a few decades. In 1301, the then King of Champa, Jaya Sinhavarman III, met the former king of the Vietnamese, Thran Nhon-Ton, who was on a pilgrimage after having left the throne to his son. He proposed to the Cham king the hand of his daughter as a gesture to show his gratitude at being so welcome, and as the King agreed, he succeeded at negociating the surrending of two northern provinces to the Vietnamese. Only, those provinces were so rebellious that they immediately caused trouble. The Vietnamese blamed Champa and invaded them in 1312. The king was taken captive and replace by his younger brother, and Champa was made a province of Annam. After a failed attempt in 1314, that resulted in the brother of the former king fleeing to Java, the viceroy, Che Anan, succeeded in driving the Vietnamese out, but didn't attempt to recover the two northern provinces.
The end of Champa: this was the start of either an amazing recovery, or the last coup by an already condemned country. After years of piece, in 1360, the new King, Che Nbong Nga, started a series of attacks on Annam, going as far as Hanoi that was saked by the Cham forces. They kept the pressure on until the death of the King in 1390. They withdrew immediately afterwards, but left the Vietnamese in disaray. Therefore, the counter-attack came only in 1402, but was then successful, until the new Chinese dynasty, the Ming, first put a halt to those attacks before conquering Annam. When the Vietnamese drove the Chinese forces away in 1428, they tried at first to maintain peaceful relations with the Chams, who had recovered the lost ground and were becoming pretty aggressive towards their western neighbors, Cambodia. However, when the Cham King died in 1441, civil war was at hand, and the Vietnamese didn't miss such an opportunity. After 30 years, the greatest part of Champa was definitely under Vietnamese domination. Far south, a small Cham state survived until 1720, when the King and his people flew once again in front before the Vietnamese forces that were headed to Cambodia.