Between 2000–1200 BC, a branch of Indo-European-speaking tribes known as the Aryans began migrating into the region. This is part of a dispute in regards to the Indo-Aryan migration. They appear to have split into Iranic peoples, Nuristani, and Indo-Aryan groups at an early stage, possibly between 1500 and 1000 BC in what is today Afghanistan or much earlier as eastern remnants of the Indo-Aryans drifted much further west as with the Mitanni. The Iranians dominated the modern day plateau, while the Indo-Aryans ultimately headed towards the Indian subcontinent. The Avesta is believed to have been composed possibly as early as 1800 BC and written in ancient Ariana (Aryana), the earliest name of Afghanistan which indicates an early link with today's Iranian tribes to the west, or adjacent regions in Central Asia or northeastern Iran in the 6th century BC. Due to the similarity between early Avestan and Sanskrit (and other related early Indo-European languages such as Latin and Ancient Greek), it is believed that the split between the old Persians and Indo-Aryan tribes had taken place at least by 1000 BC. There are striking similarities between Avestan and Sanskrit, which may support the notion that the split was contemporary with the Indo-Aryans living in Afghanistan at a very early stage. Also, the Avesta itself divides into Old and New sections and neither mention the Medes who are known to have ruled Afghanistan starting around 700 BC. This suggests an early time-frame for the Avesta that has yet to be exactly determined as most academics believe it was written over the course of centuries if not millennia. Much of the archaeological data comes from the Bactria-Margiana Archaeological Complex (BMAC and Indus Valley Civilization) that probably played a key role in early Aryanic civilization in Afghanistan.