Iyers are Tamil speaking Brahmins originating from South India. Iyers were initially confined to the state of Tamil Nadu. A few centuries back, some of them migrated and settled down in
various parts of Kerala. They integrated themselves into their new homeland and built up an identity of their own. The people of Tamil Nadu identified them as Palakkad Brahmins or Palakkad Iyers while the people of Kerala referred to them as Pattars. The term Kerala Iyers is also popular because of their presence all over Kerala.
Whatever they used to get in plenty in TN were either costly or unavailable in the new homeland. It is presumed that they had initiated changes in food habits. For example, they

started using coconut in their cooking and also substituted coconut oil for groundnut oil.
It is a very interesting fact that the coriander leaves and tomato were rarely used in Kerala and they used stored vegetables like Ash Gourd, Elephant Foot yam, Cucumber, Colacasia tubers .

coutesy:keralaiyers.com