Though tin was exported from Cornwall, bronze was not manufactured there till a comparatively late period. Bronze came from the East, and the great centre whence radiated the trade in bronze weapons was the basin of the Po. What seems to be abundantly clear is that the export of tin from Britain had come to an end by the first century of the present era. Caesar, on invading Britain, heard nothing about it, and when Britain was finally conquered, the Romans who worked the lead mines in the Mendips, and gold and copper in Wales, totally neglected Cornwall, holding it to be worthless. They never settled there, only traversed it to the Land's End, leaving behind them a couple of square camps, some coins, few and far between, and some Samian ware; but this shows little more than that a traffic went on between the Britons of Cornwall and the Romans and Romano-British beyond Exeter. The fact that the Romans had no idea that tin was to be found in the peninsula shows that the mining for it had ceased there for some time previous. The Brythonic Celts are held to have invaded Britain B.C. 300; and it is probable that from that date the industry in tin mining carried on by the Ivernian natives declined rapidly and expired, leaving not a tradition behind. It is noteworthy that the Dumnonii were behind the British peoples in the east. They had no coinage, whereas those in the south-east had theirs, copied from a stater of Philip of Macedon. No Greek coins had reached the Dumnonii, and they had consequently none to copy, however clumsily.