Ancient Indian Writing System: Though the art of writing was known to the ancient Vedic sages, it was used extensively only in the inscriptions of the Indus civilization. Excavations at Harappa, and also at Mohenjodaro indicate that the pictographic script was very well-developed. Careful investigations have further also indicated that it is comprised of four hundred characters with a variety of diacritical marks, symbols, and other signs.

Most archaeologists have also opined that this script was by far superior in its practicability as compared to its contemporaries in ancient Mesopotamia and in Egypt. The Harappa inscriptions have been found engraved on copper plates and seals and painted on pottery. But to date, no one has been able to decipher them. As a result of this, it is quite impossible at this juncture to evaluate the intellectual life of this buried culture.
Indus Valley Writing System
It can thus be asserted that the civilization of the Indus valley was highly evolved, literate and urban. Although, except for the scanty inscriptions thus far discovered, no written records are left. This was perhaps because its literature was recorded on perishable scrolls. Hence, they couldn’t stand through the test of time and thus was destroyed by natural disasters like floods, pestilences, and typhoons.
The practice of counting the number of signs revealed a lot about the type of system being used. Alphabetic systems rarely have more than 40 symbols. Syllabic systems like Linear B or Cherokee typically have 40 to 100 or so symbols. The third ranged from logo phonetic to logographic, running upwards of hundreds of signs. For example, 500 signs in Hieroglyphic Luwian, and 5000 symbols in modern Chinese.
Indus Valley Script
It appeared that the maximum number of Indus script symbols was 400. Although there were 200 basic signs, these signs were not combined with others. This meant that the Indus script was probably logo phonetic. Hence, in that, it had both signs used for their meanings, and signs used for their phonetic values.
Many signs start off as a pictorial representation of a physical object. These objects were often misleadingly called pictograms. They really are should be called logograms because they represent words in the language. However, it’s next to impossible to write out a word with abstract meaning pictorially.

What all early writers figured out was to use a logogram, not for the object or idea it was originally supposed to stand for. Instead, it was used for all words sounding similar to the original word for that object or idea.
Ancient Indian Writing System
For example, in English to write “leave” we can use a picture of a “leaf”. This is called rebus writing. It was a tremendously common pattern in all early writing systems. We could also then use the same “leaf” symbol to stand for the sound in “relief”, adding another symbol in front of the “leaf” symbol. This was to indicate the “re” sound. So the logogram gained a phonetic value as well.