The history of this country is not clearly known, and were it known it would scarcely be of sufficient importance to be related in this historical outline, but in the eighth century B.C. one monarch, named Gyges, becomes noteworthy. The country under his rule was subjected to another Aryan invasion; certain nomadic tribes called the Cimmerians came pouring across Asia Minor, and they were driven back with difficulty by Gyges and his son and grandson. Sardis was twice taken and burnt by these barbarians. And it is on record that Gyges paid tribute to Sardanapalus, which serves to link him up with our general ideas of the history of Assyria, Israel, and Egypt. Later, Gyges rebelled against Assyria, and sent troops to help Psammetichus I to liberate Egypt from its brief servitude to the Assyrians. It was Alyattes, the grandson of Gyges, who made Lydia into a considerable power. He reigned for seven years, and he reduced most of the Ionian cities of Asia Minor to subjection. The country became the centre of a great trade between Asia and Europe; it had always been productive and rich in gold, and now the Lydian monarch was reputed the richest in Asia. There was a great coming and going between the Black and Mediterranean Seas, and between the East and West. We have already noted that Lydia was reputed to be the first country in the world to produce coined money, and to provide the convenience of inns for travellers and traders. The Lydian dynasty seems to have been a trading dynasty of the type of Minos in Crete, with a banking and financial development.... So much we may note of Lydia by way of preface to the next section. § 5 Now while one series of Aryan-speaking invaders had developed along the lines we have described in Greece, Magna Græcia, and around the shores of the Black Sea, another series of Aryan-speaking peoples, whose originally Nordic blood was perhaps already mixed with a Mongolian element, were settling and spreading to the north and east of the Assyrian and Babylonian empires. We have already spoken of the arc-like dispersion of the Nordic Aryan peoples to the north of the Black and Caspian Seas; it was probably by this route that the Aryan-speaking races gradually came down into what is now the Persian country, and spread, on the one hand, eastward to India (? 2000 to 1000 B.C.), and on the other, increased and multiplied in the Persian uplands until they were strong enough to assail first Assyria (650 B.C.) and then Babylon (538 B.C.).