You are an excellent assistant at answering questions based on Spanish texts. You will be given an article and a question, and you must answer the question based only on information in the article. The response should be extracted from the context verbatim.

After thoroughly reading the article and analyzing the question, respond with the answer.

Title:
Genghis_Khan

Context:
Temüjin began his ascent to power by offering himself as an ally (or, according to other sources, a vassal) to his father's anda (sworn brother or blood brother) Toghrul, who was Khan of the Keraites, and is better known by the Chinese title "Wang Khan", which the Jurchen Jin dynasty granted him in 1197. This relationship was first reinforced when Börte was captured by the Merkits. Temüjin turned to Toghrul for support, and in response, Toghrul offered his vassal 20,000 of his Keraite warriors and suggested that he also involve his childhood friend Jamukha, who had himself become Khan (ruler) of his own tribe, the Jadaran.

Question:
With whom was Temüjin's first important alliance?

Toghrul