In addition, he subjugated several frontier kingdoms and tribal oligarchies. Lucius Marcius was sent to control those tribes that had not yet been subjugated. The institutions warred and Chronopolis subjugated the Dragonians. They too were subjugated by Assyria and the Hittites for centuries. Additionally, he left garrisons in subjugated lands. Dominant capitals exacted tribute in the form of luxury items from subjugated population centres. Because they lacked central organization, they were easily subjugated by outsiders. The Nivkhs were subjugated earlier, whereas the Ainu people submitted to the Mongols later. By 1396, they were subjugated by the Ottoman Empire. In the 13th century, the territory was subjugated by the Mongolian Empire under Genghis Khan. Then in the mid-4th century they were subjugated by the Gupta Empire under Samudragupta. After that Galdan subjugated the Black Kyrgyz and ravaged the Fergana Valley. With this the Ottomans finally subjugated and occupied Bulgaria. Coloreds formed socially distinct class different from the majority of the subjugated population. All three were eventually subjugated by future Khans.