Some tweets on the Cham kingdom & My Son temple complex.
Kingdom of Champa(192-1832) ruled over Southern and Central Vietnam, established by Cham people - an ethnic group of Austronesian origin, it was a Hinduized kingdom & culture.

https://twitter.com/DrSJaishankar/status/1265520811546488833?s=19

Hinduism arrived in this area via Funan and maritime Indian traders who settled on the Champa coast in 1st century CE. According to one rock inscription, around the beginning of the 3rd century a Hindu ruler named Sri Mara founded the kingdom of Champa.

The main religions were Hinduism, Buddhism and Chamic folk religion. The common languages were Sanskrit, Chamic languages and Old Malay.

The names of the capital cities are distinctly Hindu - Indrapura, Vijaya and Panduranga. Some of the famous kings were Bhadravarman, Rudravarman, Shambuvarman, Kandarpadharma.

As with the Kingdom of Funan in neighbouring Cambodia, Indianization escalated during the Gupta period in late 300s and 400s. Beef eating was not allowed in the kingdom. Shivaism was the most followed sect(same as Funan)

Head of Lord Shiva made around year 800 by the Cham people. It is made of an alloy of Gold and Silver

Coming on to My Son, it is a temple complex built between 4-14th century. It is dedicated to Lord Shiva.
Traditional Hindu performance at My Son temple in Vietnam

Unfortunately over 70% of the complex was destroyed in US bombing during the Vietnam war in the 1960s.
Of the once over 70 temples, only 20 remain. One of the last surviving historical places of the Cham people.

The great temple 'A1' dedicated to Lord Shiva & built in the 7th century, now in ruins.

Temples made by the Cham temples

The decline of the kingdom and the Champa people began after the Cham-Vietnamese war of 1471. Annamese(Vietnamese) from North Vietnam invaded and inflicted a crushing defeat on the Cham forces. Around 150,000 Chams were either killed or taken as slaves.

After this the kingdom of Cham lingered on in a small area of South Vietnam before being annexed by Vietnam's Nguyen Dynasty on 1832. Cham culture had declined irreparably by then. Today around 50,000 Cham Hindus live in Vietnam and few more in neighbouring countries.

Ever since the Viets won they started persecuting the Cham, something that hasn't stopped till day. So while we have civilizational connect as the good EAM says but it is with the Cham not the Viets who invaded from Southern China.
Cham are in no position to reclaim now.

Some pics of Cham Hindus in Vietnam