maybe i should quote my source,
It is an ancient kingdom of Indochina known in the past as "Lâm Â'p" ( or Lin Yi ), then Chiêm Thành ( or Tchan-Tcheng in Chinese) and located in what is now central Vietnam between Dà Nang and Phan Thiê't. The amazing Cham towers in red bricks and sandstone found in Dà Nang and Phan Thiê't are the sole silent witnesses of a civilization vanished in the turbulence of history.
The Chams were no doubts of _Indonesian_ origin and occupied the coasts of central and south Vietnam. In 2nd century, this people of sailors adopted Hinduism on contact with Indian merchants, which gave birth to the kingdom of Champa.
A Chinese traveller of 4th century described them with a particular typical physique: Big straight nose, black and curly hair, practicing a funeral ritual that consists of cremation at the sound of the drum. (ppk: which makes some speculated that they are indians, or at least, the royals are indians)
The Chàms were not only excellent sailors but also formidable builders and ingenious farmers. The Chàms arrived at achieving the unity of the country at the beginning of 5th century after having resisted several rounds of Chinese domination attempt. Their capital was located at Indrapura ( Trà Kiê?u ), near Dà Nang ( former Tourane of the French) from 7th to 9th century.
Thanks to the silk, spices, and ivory trade between China on one hand and India and the Muslim world on the other, this kingdom experienced a period of prosperity that was troubled first by the conquest of the Khmers in 1145-1147 then next by the policy of expansion of Kubilai Khan's Mongols. To face this domination, the Chàms sought alliance with Vietnam, which allowed the Chàms and the Vietnamese to come out victorious during this confrontation.
To seal this union, a Vietnamese princess of the name Huyê`n Trân of the Tran dynasty, sister of king Trâ`n Anh Tôn was proposed to become in 1306 the wife of the Champa king Chê' Mâ~n (Jaya Simhavarman) in exchange for the two Cham territories Châu Ô and Châu Ri', located at the Hai Vân Pass. These are no other than the two northern provinces Quang Tri. and Thu*`a Thiên of presently Vietnam (Huê'). This union was of short term. The Vietnamese continued to claim more land toward the South and the death of king Che Man a year after his marriage without an heir was only an additional pretext in the conquest of Champa. The king of Vietnam set up a plot by sending his general Trâ`n Kha('c Chung to rescue his sister, who had to be sacrificed according to the Cham tradition, at the funeral of her husband. The provinces of Châu Ô and Châu Ri' became then the subject of discord between Champa and Vietnam. The Chams had a burst of energy with king Chê' Bô`ng Nga ( Binasuor ) who struck the Vietnamese several times by ransacking the capital Thang Long in 1372 and 1377. But he was assassinated in 1389 during a new invasion of Vietnam and his death marked the decline of the Chams. The Vietnamese annexed this kingdom around 1470 under the Lê dynasty with king Lê Tha'nh Tôn.
In the 2nd century of Christian reckoning, the kingdom of Champa establishes itself in the area modern-day Danang. It is founded by the people of the Chams, who are _ethnically not related to the Vietnamese_ but probably have _immigrated from an area today belonging to Indonesia_. While the kingdom of Funan to the South of Champa was hardly influenced by China, the kingdom of Champa, during the 1,600 years of its history, repeatedly suffers Chinese overlordship.
Apart from that, Champa has to balance between two immediate neighbours stronger in numbers of population and in military terms: Vietnam to the North and the realm of the Khmer (Cambodians) to the South. Like Funan, the kingdom of Champa principally is a seafaring merchant power ruling over only a small land area.
In 1471 the armies of the Vietnamese Le Dynasty conquer the kingdom of Champa. About 60,000 Champa soldiers are slain, another 60,000 are abducted into Vietnamese slavery. The kingdom of Champa is reduced to a small area around the present-day Vietnamese city of Nha Trang.
When in 1720 a new attack by Vietnamese armies threatens the kingdom of Champa, the entire nation of the Cham emigrates to the Southwest, into an area north of lake Tonle Sap in present-day Cambodia.
During the Cambodian Khmer Rouge reign of terror from 1975 to 1979, some 100,000 of 250,000 Chams die or are killed.
While probably the strongest single cultural influence in Vietnam was China , the Cham civilization offers a startling contrast to many of Vietnam's Mandarin conventions. The Cham derive their cultural influences almost exclusively from India . Instead of the Confucianism and Taoism of other peoples in Vietnam, the _Cham were almost exclusively Hindu_(ppk: reasons stated above). This divergence in religion had substantial impacts in both social organization and world view.
The Cham existed from the second to the sixteenth century throughout the central highlands of Vietnam. The strongholds of Cham influence and power were centered in the Dong Nai Basin and Deo Ngang province. It is generally agreed that the kingdom was separated into five regions: Northern area, Amravati area, Vijaya Area, Kauthara Area, and Panduranga area. Even though this is a considerable portion of Vietnam, the severity of weather and limited area for agriculture limited the size of the population to about two and a half million at its height. The Cham were separated into two clans: Narikel Vamsa (Coconut Clan) and Kramuk Vamsa (Betelnut Clan). The Narikel Vamsa primarily ruled the Northern regions of the kingdom, the Kramuk Vamsa centered in the South.
Much like the Brahman cultures that flourish in India , the Cham culture utilized a caste system. The strict rigor of this system benefited the privileged Brahmans and Kshatriyas, and served to relegate untouchables to the periphery of organized life. Marriages tended to occur within the same caste with little deviation. Bodies were also cremated in a funeral pyre, called a Ghat, instead of being buried in a family grave. A striking difference from some of the older animist beliefs that already existed in Vietnam. Unlike India , however, the position of women seems to be more central to the government power structure. Chinese historians note that women held considerable power in both matters of family and marriage. At the same time the ritual of Sati was also practiced. The Cham people also adopted the Hindu practice of not eating beef -- a practice still observed in some areas of Vietnam today.
The Cham worshipped the Trinity of Brahma, Vishnu and Mahesh. In addition to this powerful trio, the Cham also paid reverence to their consorts and offspring. Shiva is the central figure of worship for most of the civilization of Champa. He is worshipped as both a figure of a man and his symbolic form, the linga. The Linga is often found in the art and architecture of the Cham people.
While the majority of the Cham people were Hindu, there is a significant minority of the population that were also Mahayana Buddhist and Islamic.
*much of the information presented in this section was obtained from the research conducted by J.C. Sharma in his text "Temples of Champa in Vietnam".