Final answer:
The city closest to the western Mongol border first arrived at by the Mongols is Samarkand, in 1220, making Option A) Samarkand, 1220 the correct answer.
Step-by-step explanation:
The closest city to the western Mongol border that was first arrived at by the Mongols is Samarkand, in the year 1220. Samarkand, 1220. Samarkand was a key city on the Silk Road, which became an important center under Mongol rule after it was incorporated into the empire through conquest.
Under the leadership of Chinggis Khan, the Mongols embarked on a campaign of expansion across Asia. Samarkand, located in the heart of the Silk Road, was conquered in 1220, which marked the first Mongol arrival in the city. This event was part of the Mongol expansion into the Khwarazmian Empire. Samarkand would then serve as a prominent urban center and was later developed further under the reign of Timur (Tamerlane), who made it his capital. The city of Samarkand was located to the south of the core Mongol territories, which makes it a plausible answer given its historical significance and geographical position.