The most important discoveries that the Gupta Empire provided to us were advances in mathematics and science. Indians of the Gupta Empire were the first to figure out the size of the moon, the spherical shape of the Earth and its gravity. They were the first people to use a number system based on 10. Furthermore in mathematics they developed the concept of zero, infinity, and other algebraic equations. The Gupta Empire was destroyed due to wars, weak rulers, and foreign invaders.
Two important subjects that the Han Dynasty brought for us were the plowing tools and the watermill. Once plowing was perfected, it helped with rudder and shipbuilding. The watermill was used to grind grains, and therefore have a better food supply. The Han Dynasty also had the first roads, canals, and bridges. Another, achievement was bringing back of the civil service exam. The major reasons why this empire collapsed were because rich people took over poor ones, people got greedy and selfish, it became too big so controlling it was very difficult. Other reasons include large land owners didn't have to pay tax, there wasn't any royalty for emperors, and roads were not cared for.
In our past, civilizations have experience points where they can just relax and have peace and stability. Think about how proud these inventors would have been to see their inventions come in use today and see how we are using these. Whenever you look at planets, thank the Indians and thank the Chinese when you see highways, watermills, and plows.