The middle kingdoms of India were the political entities in the Indian subcontinent from 230 BCE to 1206 CE. The period begins after the decline of the Maurya Empire and the corresponding rise of the Satavahana dynasty, starting with Simuka, from 230 BCE. The "middle" period lasted for almost 1436 years and ended in 1206 CE, with the rise of the Delhi Sultanate, founded in 1206, and the end of the Later Cholas (Rajendra Chola III, who died in 1279 CE).
This period encompasses two eras: Classical India, from the Maurya Empire up until the end of the Gupta Empire in 500 CE, and early Medieval India from 500 CE onwards. It also encompasses the era of classical Hinduism, which is dated from 200 BCE to 1100 CE. From 1 CE until 1000 CE, India's economy is estimated to have been the largest in the world, having between one-third and one-quarter of the world's wealth. It is followed by the late Medieval period in the 13th century.
The Northwest
During the 2nd century BCE, the Maurya Empire became a collage of regional powers with overlapping boundaries. The whole northwest attracted a series of invaders between 200 BCE and 300 CE. The Puranas speak of many of these tribes as foreigners and impure barbarians (Mlecchas). First the Satavahana dynasty and then the Gupta Empire, both successor states to the Maurya Empire, attempt to contain the expansions of the successive before eventually crumbling internally due to the pressure exerted by these wars.
The invading tribes were influenced by Buddhism which continued to flourish under the patronage of both invaders and the Satavahanas and Guptas and provides a cultural bridge between the two cultures. Over time, the invaders became "Indianized" as they influenced society and philosophy across the Gangetic plains and were conversely influenced by it. This period is marked by both intellectual and artistic achievements inspired by cultural diffusion and syncretism as the new kingdoms straddle the Silk Road.
The Indo-Greeks
The Indo-Greek Kingdom covered various parts of the Northwestern South Asia during the last two centuries BCE, and was ruled by more than 30 Hellenistic kings, often in conflict with each other.
The kingdom was founded when Demetrius I of Bactria invaded the Hindu Kush early in the 2nd century BCE. The Greeks in India were eventually divided from the Greco-Bactrian Kingdom centered in Bactria (now the border between Afghanistan and Uzbekistan).
The expression "Indo-Greek Kingdom" loosely describes a number of various dynastic polities. There were numerous cities, such as Taxila, Pushkalavati and Sagala in Pakistan's Punjab,. These cities would house a number of dynasties in their times, and based on Ptolemy's Geography and the nomenclature of later kings, a certain Theophila in the south was also probably a satrapal or royal seat at some point.
Euthydemus I was, according to Polybius a Magnesian Greek. His son, Demetrius, founder of the Indo-Greek kingdom, was therefore of Greek descent from his father at minimum. A marriage treaty was arranged for Demetrius with a daughter of Antiochus III the Great, who had partial Persian descent. The ethnicity of later Indo-Greek rulers is less clear. For example, Artemidoros Aniketos (80 BCE) may have been of Indo-Scythian descent. Intermarriage also occurred, as exemplified by Alexander the Great, who married Roxana of Bactria, or Seleucus I Nicator, who married Apama of Sogdia.
During the two centuries of their rule, the Indo-Greek kings combined the Greek and Indian languages and symbols, as seen on their coins, and blended Greek, Hindu and Buddhist religious practices, as seen in the archaeological remains of their cities and in the indications of their support of Buddhism, pointing to a rich fusion of Indian and Hellenistic influences. The diffusion of Indo-Greek culture had consequences which are still felt today, particularly through the influence of Greco-Buddhist art. The Indo-Greeks ultimately disappeared as a political entity around 10 CE following the invasions of the Indo-Scythians, although pockets of Greek populations probably remained for several centuries longer under the subsequent rule of the Indo-Parthians and Kushan Empire.
The Yavanas
The Yavana or Yona people, literally "Ionian" and meaning "Western foreigner", were described as living beyond Gandhara. Yavanas, Sakas, the Pahlavas and Hunas were sometimes described as mlecchas, "barbarians". Kambojas and the inhabitants of Madra, the Kekeya Kingdom, the Indus River region and Gandhara were sometimes also classified as mlecchas. This name was used to indicate their cultural differences with the culture of the Kuru Kingdom and Panchala.