Time Period (Date)of the Indus Civilization by fixing the date of Copper Age
The date, age, time-period and timeline during which Indus Valley Civilization (Harappan Civilization) flourished was the Copper Age which preceded the Iron Age. Nowhere in the sites so-far excavated in the region, has iron been found. Therefore we are sure that the origin of Indus civilization belonged to the Copper Age.
Dating (Age) of the Indus type seals found in Mesopotamia and Babylon and archaeological evidences
There are many problems about fixation of the time period of the Indus Valley civilization. In any case we can divide the problem of Indus chronology into two parts viz, the fixing of the upper date limit of the civilization and that of lower date limit when the civilization decayed.
As the Indus civilization had intimate contacts with the sister civilizations of the Western Asia, the date of the Indus civilization can be fixed, by fixing the date of the West Asian civilizations. As the date of main cultural period of the Sumerian civilizations is fixed 3250-2750 B. C. Sir John Marshall likes to fix the upper date of the Indus civilization as the same. Sir John Marshall’s view has been strengthened by the discovery of some archaeological evidences. Several seals similar to those of the Indus civilization have been discovered in Mesopotamia, Elam, Babylon. They are called Indus seals. The dates of these seals help us to fix the age of the Indus civilization. Mr. C. J. Gadd has dated at least twelve of these Indus seals between the years 2500-1500 B. C.
The discovery of two cylinder seals of Indus at Tell Asmar has pushed the date of the Indus civilization further back to 2800B. C. The discovery of a Sumero-Babyloinan inscription engraved on a jar found at Mohenjo-Daro has led to fix the main culture period of the Indus Civilization between 2800-2500 B .C.
Further excavations in Sind have also unearthed the remains of a civilization older than that of Mohenjo-Daro and it is called the Amri culture. Pottery remains of Amri-culture have been dated by experts as far back as 3000 B. C. The Amri culture was followed by Mohenjo-Daro and Harappa culture.
Thus, various archaeological evidences point out the antiquity of the Indus civilization to 3000 B. C. Though Dr. Fabri has fixed the main culture period of the Indus civilization as early as 2800 B. C., a culture antecedent to the Indus culture remains under subsoil water in earlier layers. A period of 500 years is allotted for this unexplored culture. So 2800+500 =3300 B. C. is regarded as the upper date limit of the Indus civilization.
Radio Carbon Test and Modern View
Recently Radio Carbon Test carried by Dr. Agarwal has cast new light on the upper date limit of the Indus civilization. Dr. Agarwal has found that C-14 test has definitely fixed the date limit of the main cultural period of the Indus civilization between 2350-2000 B.C. The scholar has pointed out that while the upper date of the Harappan culture was as above, that of Lothal, Kali Bangan was between 2200-1700 B.C. In any case the earliest date of the Harappan civilization cannot be earlier than 2400 B. C. and the most fruitful period of the civilization covered only three centuries. This view has been further confirmed by some European scholars.  Prototypes of Eagle seals of Harappa and Chanhu Daro have been found at Susa and the date are 2400 B. C.  That Indus seals have been found at Ur. Akkad, Laras in the Sargon period and the date of the Sargon period is 2316-2261 B. C and Laras 2025-1763 B. C. Thus scholars are more inclined to accept the verdict of the C-14 test and fix the upper date limit of Indus civilization between 2350-2000 B.C.
The Lower Limit of the Age of the Indus Civilization Fixed by Wheeler
We can fix the lower date of the Indus civilization on the basis of the following evidences. Iron came to be used in West Asia in the second half of the second millennium B. C. By a process of synchronism the lower date of the Indus civilization can be fixed at 1500 B.C. The probable date of the Aryan invasion of Punjab and Sind which led to the destruction of the Indus civilization is 1500 B. C. The date of the coming civilization fixed of the Aryans lends support to the theory that 1500 B. C. was the lower date limit of the Indus civilization. This is further confirmed by the generally accepted date of the Rigveda as 1400 B. C. The porcelain heads found in the upper layers of Harappa cannot be dated earlier than the 16nth century. These evidences have led Wheeler to fix the lower date of the Indus civilization as 1500 B. C.