132 HISTORY OF GRLKCE. gave them tlie price of their horses, which they sold before de parture. The operations which lie Avas now about to commence against the eastern territories of Persia were not against regular armies, but against flying corps and distinct native tribes, rely- ing for defence chiefly on the difficulties which mountains, des- erts, privation, or mere distance, would throw in the way of an assailant. For these purposes he required an increased number of light troops, and was obliged to impose even upon his heavy- armed cavalry the most rapid and fatiguing marches, such • as none but his Macedonian Companions would have been content- ed to execute ; moreover he was called upon to act less with large masses, and more with small and broken divisions. He now therefore for the first time established a regular Taxis, or division of horse-bowmen.^ Remaining at Ekbatana no longer than was sufficient for these new arrangements, Alexander re-commenced his pursuit of Da- rius. He hoped to get before Darius to the Caspian Gates, at the north-eastern extremity of Media ; by which Gates^ was un- ' Arrian, iii. 24, 1. yi^r] yiip av-ij Koi imTaKOVTiaTal Ijcav ru^ir. See the remarks of Riistow and Kochly upon the change made by Alex- ander in his military organization about this period, as soon as he found that there was no farther chance of a large collected Persian force, able to meet him in the field (Geschichte des Griech. Kriegswesens, p. 252 seq.). The change which they point out was real, — but I think they exaggerate it in degree.
- The passes called the Caspian Gates appear to be those described by
Morier, Eraser, and other modern travellers, as the series of narrow A'alleys and defiles called Ser-Desch, Sirdari, or Serdara Kahn, — on the southern- most of the two roads whicii lead eastward from Teheran towards Dama- ghan, and thence farther eastward towards Mesched and Herat. See the note of Miifzel in his edition of Curtius, v. 35, 2, p. 489; also Morier, Second Journey through Persia, p. 363; Eraser's Narrative of a Journey into Kho- rasan, p. 291. The long range of mountains, called by the ancients Taurus, extends from Lesser Media and Armenia in an easterly direction along the southern coast of the Caspian Sea. Its northern declivity, covered by prodigious forests with valleys and plains of no great breadth reaching to the Caspi- an, comprehends the moist and fertile territories now denominated Ghilan and Mazanderan. The easteni portion of Mazanderan was known in an- cient times as Hyrkania, then productive and populous ; while the moun- tain range itself was occupied by various rude and warlike tribes — Kadusii,
