The Great Himalayas covered with ice to the north of our mighty nation,form the eternal source of many river systems of India.In addition to the melting ice of Himalayas,periodical rains, specially during monsoon reason, form the source of water.
Over a period of time, these river systems have created excellent basins/plains which are of the most fertile lands in the world and support highest density in the population.
Two of the most important rivers of India i.e., "Ganga and Indus" have created a plain land i.e., Indo -Gangatic plain.The basin of the two mighty river systems is seperated by today's "Thar desert" once upon a time, a green forest.Indus was known to Indians as "Sindhu" and even today, in most part of India, it is referred as "Sindhu".
In Hindi sindhu is a synonym for 'ocean',Indus valley is referred as "Sindhu Ghati" in Hindi.Sindhu river appears to have derived its name from the "Ocean".The name Sindhu travelled to persia.They found it difficult to pronouncing the initial letter "S" and called "Sindhu" as "Hindu".
From persia, the word passed to Greece where, whole of India became known by the name of this great river "Sindhu".With the Muslim invasion,the persian name returned in the form of "Hindustan" and those who followed religion and culture of the land came to be known as "Hindus".
Punjab meaning land of five rivers(punj=five,aab=water) viz., Jhelam,Chenab,Ravi,Beas and Satulj are the tributaries to great river 'Indus'.These five tributaries had high culture spread along their banks more than 4000 years ago (Harappa), which slowly descended to lower parts of 'Indus' (Mohenjo Daro) and it even extended up to the Arabian Sea.
There are enough evidences to show that this civilization was built up by the people who lived there for thousands of years and not by the outsiders.The magnificent civilization speaks of our right and old culture.Excavation at "Harappa" in 1946 and further citadel which seems to have been used for religious and governmental purpose.
Well planned streets, strict uniformity throughout, an excellent and unique sewerage system, that was much ahead of the time were the highlights of this civilization.At Harappa, a great granary raised on a platform of 150 X 200 feet (divided in smaller blocks) has been discovered which was mainly to protect it from floods.Main food crops and today's domestic animals were known to them and were an integral part of the civilization.
There are evidences to show that this civilization was trading with Mesopotamian civilization by sea route.About 4500 years old dockyard was discovered in Gujarat at a place called "Lothal".Lothal dockyard was a tidal dock (Gujarat coast is known for its high tidal ranges) and was as sophisticated as the 'docks' of today.
There are evidences to reveal that ships from various other countries were being repaired at this dockyard.These revelations will need volumes to describe their marvels but certainly we have all the reasons to be the proud citizens of their great land of great civilization.