On the one hand, the Arabian Sea prevented some invaders, traders, and intruders from visiting Kerala; on the other hand, it attracted mostly traders from Europe and the Middle East. From historical records we know of Arabs from the eighth century and the Portuguese (1498). the Dutch. and the British from the sixteenth and the seventeenth centuries establishing trade centers in Kerala. Such ports as Cranganore,Quilon,Alleppey,Cannanore, and Cochin became prominent in later Kerala history. Most of the ancient port cities, except Cochin, are on the decline due to the lack of docking and berthing facilities as well as the expansion of other ports like Bombay and Goa, Remnants of European forts can be seen at Anjengo.

Thankasserri. Pallippuram, Tellicherry. and Cannanore. Traditionally, historians think that Kerala had a flourishing trade with Rome and Alexandria between 100 B.C. and 300 A.D. and that ports like Muziris. Tyndis, Barace, and Nelcynda referred to by Roman historians were located on the Kerala Coast. In my opinion, these ports are actually located on the Coromandel Coast where ports bearing many of the same names can be located. There is more evidence on the east coast for the presence of Roman traders than on the Kerala Coast which does not have good port facilities. Hereby I do not in any way want to diminish the importance of Cranganore. It is important to add that there is hardly any archeological evidence of a coastal civilization in Kerala before the seventh century excluding Trivandrum and Vizhinjam in South Kerala.

Kerala is rich in water supply. There are 41 rivers in the state that flow west and three rivers that are tributaries of River Kaveri and flow east. Only four rivers are more than 100 miles long. They are the Bharathapuzha (150 miles), the Periyar (142 miles), the Pamba (110 miles), and Beypore or the Chaliyar (105 miles). The average length of the other rivers is 40 miles. Many places of cultic importance are located on the banks of some of these rivers. The Mamankam-Assembly used to be held at Tirunavai on the banks of Bharathapuzha; it was here that the sacred ashes from the funerals of MahatmaGandhi and Jawaharlal Nehru were immersed in the waters.

Every year in Kumbham (February - March) at Alwaye on the shores of the Periyar, Sivaratri is celebrated. On the Pamba are located Christian places of worship like Maramon and Edathuwa. According to traditions, floods of Periyar destroyed the city of Cranganore in 1341 and prevented Tipu Sultan in 1789 from attacking Travancore during the time of Dharma Raja and Raja KesavaDasan. In recent years the rivers of Kerala have been harnessed for purposes of irrigation and electricity by technology with the construction of dams at Malampuzha, Parambikolam, Peechi, Periyar Valley, Pallivasal, Sengulam, Peringalkothu, Sabarigiri, and Idukki.

Besides rivers, Kerala has a number of natural lakes or lagoons and backwaters along the coast, which receive their water supply from rivers and streams. The important lakes from the north to the south are the following:

Kumbia, Kalnad, Bekal, Kavvai. Vembanad (the largest lake, which extendsfrom Alleppey to Cochin and is 52 miles long), Kayamkulam (19 square miles), Ashtamudi (20 square miles). The Shastamkotta Lake (1.44 square miles)/, on whose banks is the famous Shasta Temple believed to be founded by Sri Rama, is the only major natural fresh-water lake in Kerala.