mesolithic period has been found in the Bhimbetka rock shelters. Chalcolithic sites belonging to Kayatha culture () and Malwa culture (1700–1500 BCE) have been discovered in the western part of the state. Madhya Pradesh is also the world's ninth-most populous subnational entity. The city of Ujjain arose as a major centre in the region, during the second wave of Indian urbanisation in the sixth century BCE. It has served as the capital of the Avanti kingdom. Other kingdoms mentioned in ancient epicsMalava, Karusha, Dasarna and Nishadahave also been identified with parts of Madhya Pradesh. Chandragupta Maurya conquered northern India around 320 BCE, establishing the Mauryan Empire, which included all of modern-day Madhya Pradesh. Ashoka the greatest of Mauryan rulers, conquered it, bringing the region under firmer control. After the decline of the Maurya empire, the region was contested among the Sakas, the Kushanas, the Satavahanas, and several local dynasties during the 1st to 3rd centuries CE. Heliodorus, the Greek Ambassador to the court of the Shunga King Bhagabhadra erected the Heliodorus pillar near Vidisha. Ujjain emerged as the predominant commercial centre of western India from the , located on the trade routes between the Ganges plain and India's Arabian Sea ports. The Satavahana dynasty of the northern Deccan and the Saka dynasty of the Western Satraps fought for the control of Madhya Pradesh during the 1st to 3rd centuries CE. The Satavahana King Gautamiputra Satakarni inflicted a crushing defeat upon the Saka rulers and conquered parts of Malwa and Gujarat in the 2nd century CE. Subsequently, the region was conquered by the Gupta empire in the 4th and 5th centuries, and their southern neighbours, the Vakataka's. The rock-cut temples at Bagh Caves in the Kukshi tehsil of the Dhar District show the presence of the Gupta dynasty in the region, supported by the testimony of a Badwani inscription dated to the year of 487 CE. The attacks of the Hephthalites or White Huns brought about the collapse of the Gupta empire, which broke up into smaller states. The King Yasodharman of Malwa defeated the Huns in 528, ending their expansion. Later, Harsha (c. 590–647) ruled the northern parts of the state. Malwa was ruled by the south Indian Rashtrakuta Dynasty from the late 8th century to the 10th century. When the south Indian Emperor Govinda III of the Rashtrakuta dynasty annexed Malwa, he set up the family of one of