9. Khubilai Khan on the throne
One of the first difficult decisions to make for Khubilai as a ruler was what he would do with his younger brother, Arigh Böke. The other Mongolians in the Empire considered that he should execute Arigh because of treason. But Khubilai was reluctant to do this, he sent for the other leaders to have a deliberation to settle the fate of Arigh Böke. But none of these leaders said to have the time to attend because of internal problems in their own domains. The solution arrived by itself, Arigh died in 1266 CE because of illness, there were those who said that Arigh did not die of natural causes, that his death was a little too convenient. But there were no evidence that could substantiate this.As his Mongolian successors, Khubilai knew that he had to continue the expansion of the empire. His military troops were prepared for new tasks. In the eyes of the Mongolians, his ability would partly be measured in how he gained wealth, men and land to his realm. To ensure his credibility as a sovereign over the Mongolian and Chinese areas, Khubilai had to use an aggressive and firm policy.
The questions that had came up around Khubilai’s seizure of power also made it necessary to prove for the surrounding world that he was a capable ruler. He also wanted to suppress the doubts that still lingered about his credibility in his claim for the throne. There were many who questioned his place as a ruler over the Mongolian Empire. What could be better to turn such doubts if not conquering more land that could be added to the Mongolian Empire?
Khubilai’s most important goal was to take over the southern Song Empire. Even if he controlled the central part of China, he was still no ruler over the southern region of the Yangtze River. The Song Empire had a much more fertile and richer land than Northern China, trade had made its coastal cities very wealthy. Khubilai now had to subdue Song, partly to win respect from his subjects, partly to eliminate the ever-present threat that the hostile Song dynasty represented. One other reason was also the security of the borders to his empire. The southern border against Song demanded stability, if not peace. The northeastern border towards Korea was no threat, but at the time when Khubilai seized power, Korea had only just begun to acknowledge Khubilai as a sovereign.
The real threat against Khubilai’s ambitions was along the Central Asian border where Khaidu, grandson of Ögödei, constantly challenged Khubilai’s sovereignty in Central Asia and he made raids along Chinas northwestern borders. This leader of the Central Asian nomads was also troublesome to Khubilai’s northern domains, Mongolia. In 1274 CE, Khaidu made himself independent ruler over West- and Eastern Turkmenistan. This nuisance from Khaidu called for defensive measures, Khubilai kept and expanded the number of his troops, and he also started military expeditions towards northwest and north.