The term 'Iyer' is derived from 'Iyya' which means 'Sir' in Tamil and which might have beemight have been derived from 'Arya' of Sanskrit, which means a 'gentleman'. In the earliest known work dealing with grammar in Tamil - tholkappiyam (meaning old epic), the meaning of 'iyya' is given as 'a learned individual'.
Iyers were initially confined to Tamil Nadu. Though the majority of them chose to stay in Tamil Nadu itself, some of them migrated to neighboring states of Kerala, Andhra Pradesh and Karnataka. Over the years these migrants built up their own individual culture and established an identity of their own. In Kerala, they are commonly referred to as Pattars where as Iyers of Tamil Nadu call them Palakkad Brahmins. The word 'pattar' is derived from the word 'bhattar', a Sanskrit word indicating Brahmins.
The Namboothiri Brahmins of Kerala initially resisted the arrival of the Iyers into Kerala. Temple worship in Kerala is more Tantra based than Manthra. The Iyers who were not experts in this form of worship were therefore denied the posts of priests in all the temples managed by the Kerala Society. The only exception to that is of Uralikavvu (where Roudra Kali is worshipped) near Wadakancheri, Trichur District.
During the course of time, the Iyers who came to Kerala started getting increasing acceptance from Namboothiris. There is a story that Mezhattor Agnihotri, the Namboothiri member of Parachi Petta Pandeeruvar married an Iyer girl. There is also a story that a Namboothiri household accepted Uddanda as a priest. However even 50 years ago in Guruvayur temple and in many Ootupurais Namboothiri Brahmins were fed first and thereafter only the Iyers and Embrandiris. Kerala Iyers were called Paradesi Brahmins in land records.
Bhasa, the author of Swapna Vasavadatta is supposed to have lived near Trivandrum. There are reasons to believe that he was a Tamil Brahmin but certainly no proof. If this is accepted then the migration of Tamil Iyers would be much older than 350 years, may be 800 years. This is also supported by the story that the Viswanatha temple in Kalpathy was built 700 years ago.
Interestingly, the other castes of Kerala accepted the Paradesi Brahmins as a part of Kerala Culture. Nairs, and other Ambalavasi communities accepted the males as husbands. Iyer males were addressed as Swami and called as Pattars. But they were considered inferior to the Kshatriya husbands or Namboothiri husbands. In most of the Namboothiri houses the Iyers were given free food. They were also employed as cooks in their houses. It is interesting to note that among the 70 people banished from Cochin State in 1905 as a result of the Smartha Vicharam of one Thathri Kutti, ten were Tamil Iyers.
In the modern day Kerala Pattars have become an integral part of Kerala culture. There is no hatred or rancor among other communities towards them. In fact they are equal members of society. Pattars constitute one of the most educated segments of society.
Some of the proverbs in Kerala about Kerala Iyers are self-explanatory regarding the attitude of others towards them. Some of them are:
Pattaril Pottanilla -- There is no fool among Kerala Iyers.
Onnum Kanathe Pattar Kinattil Chadilla - The Kerala Iyer will not jump into the well without any aim.
And on a lighter note...
Eli, Panni, Peruchazhy, Pattar Vanaram Tatha Evaraivarum Illengil Malayalam Mahotsavam - If only rat, monkey, Bandicoot, Monkey and Kerala iyers are not there, indeed Kerala would be beautiful.
Pattars also have become very interesting characters in Malayalam literature. The most notable is their description by Kunjan Nambiar in Ottan Thullal.
They are the butt of jokes by many even during the modern times. But there is no rancor in these jokes. The common man in Kerala likes them, loves them and respects them. Along with the Nairs, Ezhavas, and Christians they are one of the most educated and moderately well off communities of modern Kerala.