When independent kingdoms were formed, they all competed for the

Middle kingdoms of India (or Classical India) refers to the political entities in India from the 3rd century BCE to the 13th century CE. This period begins after the decline of the Maurya Empire, and the corresponding rise of the Satavahana dynasty, beginning with Simuka, from 230 BCE. The "Middle" period lasts for some 1500 years, and ends in the 13th century with the rise of the Delhi Sultanate and the end of the Later Cholas (Rajendra Chola III died in 1279 CE). The period is known as the classical period of India, during which India is estimated to have had the largest economy of the world controlling between one third and one fourth of the world's wealth.

If your answers look like this a) expansion through conquestb) development of a calendar c) development of a written language d) creation of a large road workthen the answer is dhope it