Not many of us might realize it presently, but the invention of the wheel was one of the biggest events changing the life of us humans forever. Not only was it a major technological advance in the transportation sector but it also paved way for the next generation of tools using the wheel as a core component (like potters wheel, screw, clocks, motors, turbines etc).
So when was the wheel actually invented? Wikipedia says:
The wheel was originally invented in Mesopotamia in the 5th millennium BC (Ubaid period), originally in the function of potter’s wheels. Evidence of wheeled vehicles appears from the mid 4th millennium BC, near-simultaneously in Mesopotamia, the Northern Caucasus (Maykop culture) and Central Europe, so that the question which culture originally invented the wheeled vehicle remains unresolved and under debate.
And this ThinkQuest link says:
…According to archaeologists, it was probably invented in around 8,000 B.C. in Asia. The oldest wheel known however, was discovered in Mesopotamia and probably dates back to 3,500 B.C..
Now, there is a huge gap between 5th millenium and 8th millenium BC and if you consider ancient Indian scriptures like Mahabharata and Ramayana, some interesting facts (or rather anomalies) come to surface. According to some calculations the Mahabharata time was somewhere in between 850 BC – 1100 BC, whereas Aryabhatta places the event somewhere in the 4th millenium (around 3100 BC). Both these time ranges are in the Bronze Age, long after the wheel was invented.
But the Ramayana age was much earlier than Mahabharata, somewhere in the 8th millenium BC ( roughly 7200 BC). So if the wheel was invented in 5th millenium BC or later, then people in the Ramayana age could not have travelled in chariots, and there would not have been any potters too. Moreover, since we were in the Stone Age at that time, there would not have been any jewellery, ornaments, weapons, utensils or other metallic objects during the Ramayana age, and this clearly contradicts the Ramayana scriptures where fine details are given about the common usage of different metals in everyday life.
So that means Ramayana must have happened at least after the invention of the wheel and before the epic Mahabharata. Or, we need to uncover a lot of archaeological evidence in India to find out the ruins and remains of our ancient eras and get a better estimate of the important inventions like the wheel. Note that though geologists and archaeologists have done extensive surveys, digging and exploration of ancient societies based in Europe, Middle East etc, but in India we are far behind and a lot is still buried deep waiting to get uncovered. Deep digging, detailed analysis and surveying is important because if the Ramayana era indeed lies in the 8th millennium BC, then the credit of both the invention of the wheel and the precious metals like gold would go to us Indians!