Franciscan missions targeted Mongols and China, not Muslims

Evidence

It was primarily Franciscan missionaries that Pope Innocent IV and the French king Louis IX sent to negotiate with and preach to the Mongols in the midthirteenth century: one of them was William of Rubruck, whose relation of his mission Bacon put to good use. In 1289 Nicolas IV sent John of Monte Corvino to China; Franciscans continued to voyage east in the following centuries—and west as well, founding missions on the coast of California in the eighteenth century. But few of their missions were to Muslims. — John V. Tolan, Saracens, 1168

Categorization

• QUESTION: Why did Franciscan missions go around Islam to the Mongols rather than to Muslims directly — was it because martyrdom-seeking was less tempting, or because prospects looked better?