Malabar Coast, the Cholas ruled in the eastern Coromandel Coast and the Pandyas in the south-central peninsula. The Cheras were mentioned as Ketalaputo (Keralaputra) on an inscribed edict of emperor Ashoka of the Magadha Empire in the 3rd century BCE, as Cerobothra by the Greek Periplus of the Erythraean Sea and as Celebothras in the Roman encyclopedia Natural History by Pliny the Elder. The Mushika kingdom existed in northern Kerala, while the Ays ruled south of the Chera kingdom. Trade relations The region of Kerala was possibly engaged in trading activities from the 3rd millennium BCE with Arabs, Sumerians and Babylonians. Phoenicians, Greeks, Egyptians, Romans, and Chinese were attracted by a variety of commodities, especially spices and cotton fabrics. Arabs and Phoenicians were the first to enter Malabar Coast to trade Spices. The Arabs on the coasts of Yemen, Oman, and the Persian Gulf, must have made the first long voyage to Kerala and other eastern countries. They must have brought the Cinnamon of Kerala to the Middle East. The Greek historian Herodotus (5th century BCE) records that in his time the cinnamon spice industry was monopolized by the Egyptians and the Phoenicians. Muziris, Tyndis, Naura, Berkarai, and Nelcynda were among the principal trading port centres of the Chera kingdom. Megasthanes, the Greek ambassador to the court of Magadhan king Chandragupta Maurya (4th century BCE) mentions Muziris and a Pandyan trade centre. Pliny mentions Muziris as India's first port of importance. According to him, Muziris could be reached in 40 days from the Red Sea ports of Egypt purely depending on the South west monsoon winds. Later, the unknown author of the Periplus of the Erythraean Sea notes that "both Muziris and Nelcynda are now busy places". There were harbours of Naura near Kannur, Tyndis near Kozhikode, and Barace near Alappuzha, which were also trading with Rome and Palakkad pass (churam) facilitated migration and trade. Tyndis was a major center of trade, next only to Muziris, between the Cheras and the Roman Empire. Roman establishments in the port cities of the region, such as a temple of Augustus and barracks for garrisoned Roman soldiers, are marked in the Tabula Peutingeriana; the only surviving map of the Roman cursus publicus. Pliny the Elder (1st century CE) states that the port of Tyndis was located at the northwestern border of Keprobotos (Chera dynasty). The North Malabar region, which lies north of the