of modern Malayalam literature) who was born in Tirur, one of the most important works in Malayalam literature. Unnunili Sandesam written in the 14th century is amongst the oldest literary works in Malayalam language. Cherusseri Namboothiri of 15th century (Kannur-based poet), Poonthanam Nambudiri of 16th century (Perinthalmanna-based poet), Unnayi Variyar of 17th–18th centuries (Thrissur-based poet), and Kunchan Nambiar of 18th century (Palakkad-based poet), have played a major role in the development of Malayalam literature into current form. The words used in many of the Arabi Malayalam works, which dates back to 16th–17th centuries are also very closer to modern Malayalam language. The basin of the river Bharathappuzha, which is otherwise known as River Ponnani, and its tributaries, have played a major role in the development of modern Malayalam Literature. By the end of the 18th century some of the Christian missionaries from Kerala started writing in Malayalam but mostly travelogues, dictionaries and religious books. Varthamanappusthakam (1778), written by Paremmakkal Thoma Kathanar is considered to be the first travelogue in an Indian language. The modern Malayalam grammar is based on the book Kerala Panineeyam written by A. R. Raja Raja Varma in late 19th century CE. Folk Songs For the first 600 years of the Malayalam calendar, Malayalam literature remained in a preliminary stage. During this time, Malayalam literature consisted mainly of various genres of songs (Pattu). Folk songs are the oldest literary form in Malayalam. They were just oral songs. Many of them were related to agricultural activities, including Pulayar Pattu, Pulluvan Pattu, Njattu Pattu, Koythu Pattu, etc. Other Ballads of Folk Song period include the Vadakkan Pattukal (Northern songs) in North Malabar region and the Thekkan Pattukal (Southern songs) in Southern Travancore. Some of the earliest Mappila songs (Muslim songs) were also folk songs. Old and Middle Malayalam The earliest known poems in Malayalam, Ramacharitam and Thirunizhalmala, dated to the 12th to 14th century, were completed before the introduction of the Sanskrit alphabet. It was written by a poet with the pen name Cheeramakavi who, according to poet Ulloor S Parameswara Iyer, was Sree Veerarama Varman, a king of southern Kerala from AD 1195 to 1208. However the claim that it was written in Southern Kerala is expired on the basis of new discoveries. Other experts, like Chirakkal T Balakrishnan Nair, Dr. K.M. George, M. M. Purushothaman Nair, and P.V. Krishnan Nair, state that the origin of the book