Hulagu advanced to continue this victory and met the enemy north of Derbend near the Caspian. Nogai was put to flight and pursued by a large force of warriors who seized a camp left by him north of the Terek in which were vast numbers of cattle and of women and children. Hulagu’s army remained at that camp and for three days continued to drink, and to yield themselves up to every indulgence accessible. All on a sudden Nogai reappeared with his army. Hulagu’s men were surprised near the river and thoroughly defeated (January 13, 1263). The only escape for survivors was to cross the frozen river. They tried this, the ice broke and immense numbers sank in the Terek. Hulagu returned to Tebriz greatly grieved and cast down by the overthrow, but he summoned at once a new army and avenged his wrath on those merchants of Kipchak whom he found in Tebriz at his coming. He put them to death, and then seized their property. Berkai answered straightway by killing all traders within his reach who were subjects of Hulagu, and living in Kipchak. Hulagu next killed Bokhara people. Population had grown in that city, though not greatly, since its ruin. It reached seventeen thousand according to a census. Of these five thousand were subjects of Kipchak, three thousand belonged to Siurkukteni, the mother of Hulagu, and the rest to the Grand Khan. Hulagu commanded that those five thousand subjects of Berkai be driven to the plains near the city; there the men were slaughtered with swords; the women and children were reduced to captivity. In 1264, the year following, report ran that Nogai was to lead an attack on lands south of the Caucasus. While Hulagu was preparing to meet this, Jelal ud din, son of the second chancellor to the late Kalif, told Hulagu that there were thousands of Kipchaks then living in Persia who would serve in the vanguard with readiness. They knew northern methods of warfare, and would be, as he said, of use beyond others in the campaign against Berkai. Hulagu sent this man to summon those warriors, and commanded that supplies, arms, and money be given him in sufficiency, and that no one should thwart him. When Jelal had assembled those people of Kipchak he declared that Hulagu would put them in the vanguard to be slain there. “I do not wish this,” said he. “Follow me and we will free ourselves from Mongols.” He gave the men money and arms from the treasury and arsenals of Bagdad; then, he told the commandant of the city that to gather provisions he was making a raid against Kafadje Arabs, at war with Hulagu; that done, he would march toward Shirvan. He crossed the Euphrates, all his men following, taking with them their families and baggage. Then he declared to them that he was going to Syria and Egypt. Hulagu was beside himself with anger when he learned of Jelal’s treachery.