But a further and a greater importance attaches to them. Since the important discovery, in 1824, by Colonel Tod, that Greek coins had once been struck in India, the names of thirty-three Greek and twenty-six[11] Indo-Scythia nor Śaka and Indo-Parthian or Pahlava princes, ruling territories round the Indian frontier, have gradually been recovered from coin legends, and not more than half-a-dozen of these are known from other sources. Even the names of the later Kushāṇa kings were first deciphered from their coins. Thus coins alone have been responsible for the recovery of a whole period of Indian history. Probably no class of Indian coins has attracted more attention or been subjected to more patient examination than these, which mark the first intermingling of Eastern and Western culture in India; yet, as the relationship of the different kings and dynasties who minted them, their dates, and the territories over which they ruled are still largely matters of conjecture, it will be well to sketch in outline the probable course which events took in Northern India and the adjacent countries from the time of Alexander to the first century of our era. In October, 326 B.C., Alexander began his retreat from the Panjāb. To commemorate his victories he struck a medal;[12] about the same time an Indian prince, Sophytes (Saubhūti), struck a silver coin (Pl. II, 1) in the Greek style; with these two exceptions scarcely a mark or lasting trace of his invasion remained. Eleven years after Alexander’s death his general, Seleucos, founded the Seleucid kingdom of Syria. Between the years 250-248 B.C. two of the chief Syrian provinces revolted and became independent kingdoms, Bactria under Diodotos and Parthia under Arsakes, both events fraught with important consequences for India and her coinage. The fourth Bactrian king, Demetrios (c. 190-150 B.C.), son of Euthydemos, as the Mauryan Empire fell into decay, was able to extend his kingdom as far as the Panjāb, and assumed the title of “King of the Indians.” But about the same time he was confronted with a rival, Eukratides (c. 175-155 B.C.), who deprived him of his Bactrian dominions, and even of a portion of Gandhāra (the present districts of Peshāwar and Rawalpindi). Henceforward there were two rival Greek dynasties, the house of Eukratides, including the princes Heliokles, Antialkidas and Hermaios, ruling in Kābul, Kandahār and Gandhāra, and the house of Euthydemos, of whom the principal rulers were Apollodotos, Menander, Strato I, Zoilos and Hippostratos, in East Gandhāra and the Panjāb. Pantaleon, Agathokles and Antimachos, of the latter family, appear to have been petty princes ruling north of Kābul (c. 155-140 B.C.), and there must have been similar small principalities elsewhere, whose rulers were contemporary. About the year 135 B.C. Heliokles, the last king of Bactria, was driven out of that country by a Scythian tribe, the Śakas, and fixed the headquarters of his rule at Kābul,