Why are Tamils trying to break up the only country for Sinhalese when Tamil Nadu exists?

 Tamils are the victims by Sri Lankan Nationals.

Yes.

Sri Lankan Population is only 2 Cr, one fourth of Indian State of TN. And Tamils are about 4% or 8 lakhs. (Chennai population is 1 crore).

Let us see the break up of demographics in timeline:

In 1931,

Sinhalese :65%

Indian Plantation Tamils:15%

Sri Lankan Tamils:11%

Moors:5%

Description of who is who and what has happened from 1931 till 2012:

The Sinhalese make up 74.9% (up from 65%) of the population and are concentrated in the densely populated south-west and central parts of the island.

Sri Lankan Tamils (Malayalis migrated to Sri Lanka in 12th century, they speak Malayalam and Tamil scripts are used for writing. They alongwith Sinhalese raised the voice in 1960s to drive out Tamils from Sri Lanka) who live predominantly in the North and East of the island, form the largest minority group remained same from 1931,at 11.1% (according to the 2012 census) of the population.

The Moors descendants of Arab traders that settled in Sri Lanka and married local women, form the third largest ethnic group at 9.3% (up from 5%)of the population.

There are also Indian Tamils who form a distinct ethnic group comprising 4.1% (down from 15% in 1931)of the population.

The British brought them to Sri Lanka in the 19th century as tea and rubber plantation workers, and they remain concentrated in the "tea country" of south-central Sri Lanka.

What is the reason for the decline from 15% to 4%:

In 1960s Sri Lankan Tamils ( Malayalis who migrated to Sri Lanka in 12th century. they speak Malayalam and Tamil scripts are used for writing) alongwith Sinhalese raised the voice in 1960s to drive out Tamils from Sri Lanka.

The Indian Tamils of Sri Lanka were considered to be "stateless" and over 300 000 Indian Tamils were deported back to India, due to the agreement between Sri Lanka and India in 1964. Remaining were made Sri Lankan citizens in trenches till 2003.

Muthiah Muralidharan is a Sri Lankan, and an Indian Tamil whose ancestors migrated to Sri Lanka.

Andimuthu Raja is an Indian politician, and an Indian Tamil whose ancestors migrated to Sri Lanka and his grand father returned to India in 1960.

In a nation of 2 cr population where majority (Sinhalese) cannot take along the minorities and another minority(Sri Lankan Malayalis) alongwith majority drive out Tamils and made them stateless.

Karma strike back From 1980s. Majority turned against Minority Sri Lankan Malayalis is another history and now they fight with Sinhalese on Tamil identity.

Now Tamil Nadu is supporting Sri Lankan Malayalis who made Tamils stateless in 1964. Mainland TN is against Own Indian Tamils for the sake of Sri Lankan Malayalis, thanks to Seeman who also has Malayala ancestry.

Demographic statistics speak themselves, who made Tamils victim

In 2012,

Sinhalese : 75% up from 65%

Indian Plantation Tamils:4% down from 15%

Sri Lankan Tamils:11% flat 11%

Moors:9% up from 5%

Tamils are the victims by Sri Lankan Nationals, both Sinhalese and Sri Lankan Malayalis.