In which year was the Indus Valley (Harappan) civilisation first discovered by modern archaeologists?

Introduction / Context:
The discovery of the Indus Valley (Harappan) civilisation is one of the most important milestones in the study of ancient India. Until the early 20th century, many scholars believed that Indian civilisation began with the Vedic period. The excavation of Harappa and Mohenjo-daro fundamentally changed that picture by revealing an even earlier urban civilisation. Knowing the year when this discovery was first formally recognised is a common general-knowledge and history exam question.

Given Data / Assumptions:

• The question asks for the year in which the Indus Valley civilisation was discovered.
• The options are 1901, 1921, 1935 and 1942.
• We assume the learner knows that Harappa was the first site to be identified as part of this ancient civilisation.
• The focus is on the year of this initial archaeological discovery, not on later excavations.

Concept / Approach:
Harappa, located in present-day Pakistan, was excavated by archaeologist Daya Ram Sahni under the Archaeological Survey of India. The crucial year when the remains were recognised as belonging to a previously unknown ancient urban civilisation is 1921. This was soon followed by the discovery and excavation of Mohenjo-daro. Although there had been earlier minor findings and reports, 1921 is the year generally cited as the official “discovery” of the Indus Valley civilisation in standard history textbooks and exam guides.

Step-by-Step Solution:
Step 1: Recall that Harappa was the first major site excavated that revealed a Bronze Age urban civilisation in the Indus region. Step 2: Identify Daya Ram Sahni as the archaeologist who led the 1921 excavation at Harappa under the Archaeological Survey of India. Step 3: Understand that this excavation brought to light planned streets, brick structures and artefacts that indicated a previously unknown civilisation. Step 4: Note that subsequent excavations, such as at Mohenjo-daro under R.D. Banerji, confirmed and extended these findings. Step 5: Compare the given years and recognise that 1921 is the historically accepted date for the formal discovery. Step 6: Conclude that 1921 is the correct answer.

Verification / Alternative check:
Indian history textbooks and archaeological histories consistently state that the Indus Valley civilisation, also called the Harappan civilisation, was discovered in 1921 when Harappa was excavated. Some texts mention earlier observations of mounds or bricks, but they underline that only in 1921 did excavations clearly identify the remains of a large, ancient urban culture. Later years, such as 1935 or 1942, correspond to continued research, not to the initial discovery. Therefore, 1921 is the standard year cited in exams.

Why Other Options Are Wrong:

• 1901: Too early; systematic excavations revealing the Harappan civilisation had not yet been conducted.
• 1935: By this time more sites were being explored, but the initial discovery had already taken place in 1921.
• 1942: Even later; by then the existence of the Indus civilisation was well established.

Common Pitfalls:
Some students confuse 1921 with 1922 (often associated with Mohenjo-daro) or mix up different dates related to the Archaeological Survey of India. Others may guess a later date, thinking that such a major discovery must have happened closer to independence. To avoid mistakes, memorise the pairing: Harappa excavation and formal discovery of the Indus Valley civilisation in 1921.

Final Answer:
The Indus Valley (Harappan) civilisation was first discovered by modern archaeologists in 1921.