such as Asko Parpola connect the Dasas and Dasyus to Iranian tribes Dahae and Dahyu and believe that Dasas and Dasyus were early Indo-Aryan immigrants who arrived into the subcontinent before the Vedic Aryans. Likwise, Bronkhorst has argued that the central Ganges Plain was dominated by a related but non-Vedic Indo-Aryan culture, a difference also noted by Samuel. Accounts of military conflicts in between the various tribes of Vedic Aryans are also described in the Rigveda. Most notable of such conflicts was the Battle of Ten Kings, which took place on the banks of the river Parushni (modern day Ravi). The battle was fought between the tribe Bharatas, led by their chief Sudas, against a confederation of ten tribes. The Bharatas lived around the upper regions of the river Saraswati, while the Purus, their western neighbours, lived along the lower regions of Saraswati. The other tribes dwelt north-west of the Bharatas in the region of Punjab. Division of the waters of Ravi could have been a reason for the war. The confederation of tribes tried to inundate the Bharatas by opening the embankments of Ravi, yet Sudas emerged victorious in the Battle of Ten Kings. The Bharatas and the Purus merged into a new tribe, the Kuru, after the war. Later Vedic period (c. 1000 – c. 600 BCE) After the 12th century BCE, as the Rigveda had taken its final form, the Vedic society, which is associated with the Kuru-Panchala region but were not the only Indo-Aryan people in northern India, transitioned from semi-nomadic life to settled agriculture in north-western India. Possession of horses remained an important priority of Vedic leaders and a remnant of the nomadic lifestyle, resulting in trade routes beyond the Hindu Kush to maintain this supply as horses needed for cavalry and sacrifice could not be bred in India. The Gangetic plains had remained out of bounds to the Vedic tribes because of thick forest cover. After 1000 BCE, the use of iron axes and ploughs became widespread and the jungles could be cleared with ease. This enabled the Vedic Aryans to extend their settlements into the western area of the Ganga-Yamuna Doab. Many of the old tribes coalesced to form larger political units. The Vedic religion was further developed with the emergence of the Kuru kingdom, systematising its religious literature and developing the Śrauta ritual. It is associated with the Painted Grey Ware culture