The earliest evidence of progress in science and technological progress in the Indian subcontinent is evident from the remains of the Harappan civilization. These remains range from 4000 to 3000 BC.
The various inscriptions help us infer that ports such as Lothal were developed as export centers of early manufactured products. These manufactured products were made from smelted copper and bronze.
Kilns for smelting copper ingots and casting tools were in existence. Similarly, even metal tools such as curved or circular saws, pierced needles were also common. Most significant among these were the bronze drills with twisted grooves. The drill enabled the production of items with unparalleled precision for the times. Hence they could be regarded as an ancient precursor of the modern machine tool.
Urban centres in the Harappan region traded with each other. In addition, they also traded with their counterparts in Babylon, the Persian Gulf, Egypt and possibly the Mediterranean. The span of the Harappan civilization was quite extensive. These included much of modern Sindh, Gujarat, Rajasthan, Haryana, Punjab and Western UP.
The archeological excavations have been carried out from time to time. From such excavations, it is amply clear that the ancient Harappans made use of accurate weights and measures.The people of the Indus Civilization achieved great accuracy in measuring length, mass, and time.
They were among the first to develop a system of uniform weights and measures. Their measurements were extremely precise. Their smallest division, which is marked on an ivory scale found in Lothal. This was approximately 1.704mm, the smallest division ever recorded on a scale of the Bronze Age.
Harappan engineers followed the decimal division of measurement for all practical purposes. These included the measurement of mass as revealed by their hexahedron weights.
Brick sizes were in a perfect ratio of 4:2:1. The decimal system also came to be used. Weights were based on units of 0.05, 0.1, 0.2, 0.5, 1, 2, 5, 10, 20, 50, 100, 200, and 500. Each unit weighed approximately 28 grams, similar to the English Imperial ounce or Greek uncial. Smaller objects were weighed in similar ratios with the units of 0.871.
Unique Harappan inventions include an instrument which was used to measure whole sections of the horizon and the tidal dock. In addition, they evolved new techniques in metallurgy. Metals like copper, bronze, lead, and tin were produced. The engineering skill of the Harappans was remarkable. This was evident particularly in building docks after a careful study of tides, waves, and currents.
In 2001, archaeologists studying the remains of two men from Mehrgarh, Pakistan made the startling discovery. They discovered that the people of the Indus Valley Civilization, even from the early Harappan periods, had knowledge of medicine and dentistry as well.