The Mongols under which famous leader invaded Transoxiana and regions of north-east Iran in 1219 during their westward expansion?

Introduction / Context:
The Mongol conquests of the thirteenth century reshaped the history of Asia and Europe. One major phase of this expansion was the invasion of Transoxiana and north-east Iran in the early 1200s, which opened the way for Mongol influence from Central Asia into the Islamic world. This question tests knowledge of which specific leader directed the Mongols during the invasion of 1219.

Given Data / Assumptions:

- The year mentioned is 1219. - The region named is Transoxiana and north-east Iran. - The options are Timur Lang, Nadir Shah, Ahmed Shah Abdali and Genghis Khan. - We assume standard chronology of major Central Asian conquerors.

Concept / Approach:
Transoxiana, the region between the Amu Darya and Syr Darya rivers, was one of the first major targets of the western campaigns of Genghis Khan. In 1219 he launched an invasion against the Khwarazmian Empire after a series of diplomatic and commercial disputes. Timelines of world history place Timur Lang, Nadir Shah and Ahmed Shah Abdali several centuries after Genghis Khan. Therefore, by matching the date and region with the correct conqueror, we can confidently identify the Mongol leader responsible for the 1219 invasion.

Step-by-Step Solution:
Step 1: Recall that Genghis Khan founded and led the early Mongol Empire in the late twelfth and early thirteenth centuries. Step 2: Note that the westward campaigns against Central Asian Islamic states, including the Khwarazmian Empire, began around 1219. Step 3: Understand that Timur Lang (Tamerlane) lived in the fourteenth century and led later Central Asian campaigns, long after Genghis Khan. Step 4: Nadir Shah and Ahmed Shah Abdali were eighteenth century rulers from Iran and Afghanistan respectively, associated with raids on India, not with the early Mongol conquests. Step 5: Therefore, the only leader in the options who fits both the date 1219 and the Mongol invasion of Transoxiana is Genghis Khan.

Verification / Alternative check:
World history surveys highlight that in 1219 Genghis Khan attacked the Khwarazmian ruler Muhammad II, whose domains included Transoxiana and parts of Iran. The Mongol armies captured cities like Bukhara and Samarkand and devastated large areas. In contrast, Timur, although often confused with the Mongols, ruled much later and sometimes claimed legacy from Genghis, which can mislead readers. Nadir Shah and Ahmed Shah Abdali are linked more to eighteenth century invasions of India from the north-west. This comparison confirms Genghis Khan as the correct answer.

Why Other Options Are Wrong:
Timur Lang: A Turko-Mongol conqueror of the fourteenth century, famous for campaigns in Persia and India, but not the leader of the 1219 Mongol invasions.
Nadir Shah: An eighteenth century Iranian ruler known for the 1739 sack of Delhi, not a thirteenth century Mongol leader.
Ahmed Shah Abdali: Founder of the Durrani Afghan Empire and an eighteenth century invader of India, again far removed in time from 1219.

Common Pitfalls:
Because Timur Lang and Genghis Khan were both Central Asian conquerors and sometimes linked in legends, students may confuse their periods. Another pitfall is to associate any attack on Iran or Central Asia with later invaders like Nadir Shah. Keeping a simple chronological order in mind Genghis Khan (thirteenth century), Timur (fourteenth century), Nadir and Abdali (eighteenth century) helps avoid these errors.

Final Answer:
The Mongols who invaded Transoxiana and north-east Iran in 1219 were led by Genghis Khan.