In the Delhi Sultanate period, the silver coin known as the ‘‘tanka’’ was first formally introduced by which ruler?

Introduction / Context:
This question concerns the monetary history of the Delhi Sultanate and the introduction of standard coinage. The silver tanka and copper jital became important units of currency under the early Sultans. Knowing which ruler was responsible for introducing the silver tanka helps students link economic reforms with key personalities in medieval Indian history.

Given Data / Assumptions:

• The coin mentioned is the silver tanka.
• The context is the Delhi Sultanate period, not later Mughal or regional kingdoms.
• The options include Qutb-ud-din Aibak, Iltutmish, Balban and Bahram Shah.
• The question asks who first introduced this silver coin.
• We assume that the standard textbook narrative of Delhi Sultanate coinage is being followed.

Concept / Approach:
Iltutmish, who reigned in the early 13th century, is known as one of the real consolidators of the Delhi Sultanate. He is credited with introducing a proper currency system, including the silver tanka and the copper jital, which remained influential for later Muslim rulers in India. Qutb-ud-din Aibak, his predecessor, laid the political foundations but did not establish as stable a coinage system. Balban and Bahram Shah were later rulers who did not have the same reputation for currency reforms as Iltutmish. Therefore, correctly identifying the ruler requires recognising Iltutmish's special role in standardising the coinage.

Step-by-Step Solution:
Step 1: Place the rulers chronologically: Qutb-ud-din Aibak first, followed by Iltutmish, then Bahram Shah and later Balban. Step 2: Recall that Iltutmish is considered the real founder and organiser of the Delhi Sultanate's administration. Step 3: Remember that he introduced the silver tanka and copper jital as recognised currency units. Step 4: Observe that no similar major coin reform is attributed to Qutb-ud-din Aibak, Balban or Bahram Shah in standard accounts. Step 5: Therefore, select Iltutmish as the ruler who introduced the silver tanka.

Verification / Alternative check:
Histories of medieval Indian coinage and Delhi Sultanate administration consistently mention that Iltutmish introduced the silver tanka (weighing about 175 grains) and the copper jital, forming the basis of a stable currency system. This reform is often highlighted alongside his political achievements like recognising Delhi as a sovereign sultanate and gaining formal investiture from the Abbasid Caliph. By contrast, Qutb-ud-din Aibak is remembered for construction and military achievements, not major coinage innovations, and Balban for his strong centralised rule and strict court discipline.

Why Other Options Are Wrong:
Qutb-ud-din Aibak: As the first ruler of the Delhi Sultanate, he did not systematise coinage in the same way and is not credited with the introduction of the silver tanka.
Ghiyas-ud-din Balban: A later Sultan, known for his policy of kingship and suppression of nobles, but not for pioneering the tanka coin.
Bahram Shah: A relatively weak ruler in the line of Iltutmish, without major currency reforms attributed to his reign.

Common Pitfalls:
Students sometimes assume that the founder of a dynasty or the most famous strong ruler must automatically be responsible for all key reforms. This can lead them to choose Aibak or Balban by guesswork. To avoid such errors, it is important to remember specific associations: Iltutmish equals coinage reforms (tanka and jital), Balban equals strict monarchy, and Aibak equals early conquests and monumental architecture like the Qutb complex.

Final Answer:
The silver tanka was first introduced in the Delhi Sultanate by Iltutmish.