Nathaman Udayar is one sub caste of Parkavakulam

Parkavakulam

-Parkavakulam:Parkavakulam ,பார்க்கவகுலம் a Tamil-speaking community from the Indian state of Tamil Nadu. The main sub-divisions of the community are Nathaman, Nainar, Malaiyaman, Suruthiman, Moopanar...

 community of Tamil Nadu

Tamil Nadu

Tamil Nadu is one of the 28 states of India. Its capital and largest city is Chennai. Tamil Nadu lies in the southernmost part of the Indian Peninsula and is bordered by the union territory of Pondicherry, and the states of Kerala, Karnataka, and Andhra Pradesh...

, India

India

India , officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country with over 1.2 billion people, and the most populous democracy in the world...

. The others are Moopanar, Nainar

Nainar

Nainar is an Indian word which can refer to the following:*a title given to Tamil Jains living in Tamil Nadu*a sub-caste of the Parkavakulam community in Tamil Nadu*Sankara Nainar, an image of Perumal in Sankaran Koil...

, Malayaman

Malayaman

The Malayamān family dynasty of the Velir royal house were chiefs who ruled Nadu Naadu of Tamilakkam during the Sangam period and worked closely with the early Cholas of the Chola Dynasty and the Chera Dynasty. Chiefs of this dynasty readily took the title Chēdirāyan, and delighted in their rule...

 and Shruthiman. Nathaman traditionally engaged in Agriculture. Most of the Nathaman followed Shaivism

Shaivism

Shaivism is one of the four major sects of Hinduism, the others being Vaishnavism, Shaktism and Smartism. Followers of Shaivism, called "Shaivas," and also "Saivas" or "Saivites," revere Shiva as the Supreme Being. Shaivas believe that Shiva is All and in all, the creator, preserver, destroyer,...

 and the reminder followed Vaishnavism

Vaishnavism

Vaishnavism is a tradition of Hinduism, distinguished from other schools by its worship of Vishnu, or his associated Avatars such as Rama and Krishna, as the original and supreme God....

. Christians can be also found.
They are the people of the chola dynasty

Chola Dynasty

The Chola dynasty was a Tamil dynasty which was one of the longest-ruling in some parts of southern India. The earliest datable references to this Tamil dynasty are in inscriptions from the 3rd century BC left by Asoka, of Maurya Empire; the dynasty continued to govern over varying territory until...

 and cholas were now called as udayar mentioning the whole as parkavakulam community. King Rajaraja Cholan was called as Periya Udayar.