Which of the following was not a characteristic feature of the Indus Valley (Harappan) Civilization?

Introduction / Context:
This question deals with the material culture of the Indus Valley or Harappan Civilization, one of the earliest urban civilisations in the Indian subcontinent. Archaeological findings tell us what materials, metals, building techniques and town planning methods the Harappans used. Identifying which feature does not belong to this civilisation requires a basic understanding of its chronological position in relation to the Bronze Age and the later Iron Age.

Given Data / Assumptions:

• The focus is on characteristic features of the Indus Valley Civilization.
• Options include use of iron, town planning, drainage system and use of bronze.
• The question asks which one was not a feature.
• We assume knowledge that the Harappans flourished during the Bronze Age.

Concept / Approach:
The Indus Valley Civilization is generally dated to about 2600–1900 BCE for its mature phase, a period firmly within the Bronze Age. Excavations show extensive use of baked bricks, carefully laid out streets and advanced drainage systems. Copper and bronze tools, weapons and ornaments are common. By contrast, iron appears in the subcontinent much later, in the early Iron Age, after the Harappan urban centres had already declined. Therefore, the use of iron cannot be considered a feature of the Indus Valley Civilization.

Step-by-Step Solution:
Step 1: Recall that the Harappan Civilization belongs to the Bronze Age, not the Iron Age. Step 2: Recognise that town planning with a grid pattern of streets and organised housing is a well known feature of Harappa and Mohenjo daro. Step 3: Remember that an advanced drainage system, with covered drains and soak pits, is one of the most striking features of Harappan cities. Step 4: Note that bronze objects, made from copper and tin, have been unearthed in large numbers at Harappan sites. Step 5: Conclude that "use of iron tools and weapons" is the one option that does not match Harappan characteristics.

Verification / Alternative check:
Archaeological reports on Harappan sites consistently refer to copper and bronze artefacts, but iron objects are absent in the mature Harappan layers. Iron becomes common only in later cultures such as the Painted Grey Ware and early historic periods. Textbooks also emphasise town planning and drainage as signature achievements of the Indus cities. These consistent findings confirm that the use of iron was not a feature of the Indus Valley Civilization.

Why Other Options Are Wrong:
Carefully planned town layouts: Harappan cities like Mohenjo daro and Harappa are famous for their grid pattern streets, zoning and planned layout, so this is indeed a feature.
Well organised drainage system: Covered drains along streets and sophisticated waste disposal arrangements are a hallmark of Harappan urban life.
Extensive use of bronze: The civilisation is classified as Bronze Age precisely because bronze tools, weapons and artefacts are common in excavations.

Common Pitfalls:
Students sometimes assume that any advanced civilisation must have used iron, overlooking the chronological distinction between the Bronze and Iron Ages. Another common mistake is to underestimate how advanced Harappan town planning and drainage were, and to think they might be later features. Keeping a clear timeline of copper bronze culture followed by iron usage helps avoid these misunderstandings in exam questions.

Final Answer:
The feature that did not belong to the Indus Valley Civilization was the use of iron tools and weapons.