Task: Question Understanding
Input (English): Passage: The uprising greatly reduced the Tver Principality's power in the northeastern remains of Kievan Rus'. In 1328, Öz Beg granted Ivan Kalita the duchies of Novgorod and Kostroma. Alexander Vasilyevich, the prince of Suzdal, received Vladimir and a region encompassing present day Nizhny Novgorod and Gorodets. By granting the more prestigious Vladimir to the weaker of the two princes, Öz Beg maintained adherence to the principle of "divide and rule," reasoning that Moscow's jealousy of Suzdal's lands would prevent them from allying to fight against the Golden Horde. Alexander moved to Sweden after his time in Lithuania, and then back to Pskov after the city's excommunication was lifted, under the patronage of Gediminas, Grand Duke of Lithuania. In 1335, he gained forgiveness from Öz Beg and was allowed to return to his former position in Tver, however by then, the state had lost most of its influence, being replaced by the Grand Duchy of Muscovy. This return did not last long, as both Alexander and his son Fyodor were taken to Sarai and quartered in 1339. Following the execution of Alexander Vasilievich in 1331, Ivan received the duchy of Vladimir and became the sole ruler of northeastern Russia. Favor from the khan of the Golden Horde allowed Moscow to gain power rapidly at the expense of Tver, with Tver eventually losing all influence to Moscow. However, a new rivalry was formed between the princes of Suzdal-Nizhny Novgorod. The relative power of Moscow and their strong alliance with the Horde led to a period of relative peace in Russia that was not interrupted until the reign of Dmitry Donskoy, the first prince of Moscow to openly challenge the Horde. He would later defeat them at the Battle of Kulikovo in 1380.
Question: Why was Alexander Vasiliveich taken to Sarai?
Output (English): span