Hinduism is typically taught through a historical lens. We are told that there was a Harappan period 4,000 years ago, followed by Vedic Period 3,000 years ago, followed by the Puranic Age, which began 2,000 years ago, which was then followed by the Bhakti Age 1,000 years ago. This was followed by the Reform Movement in colonial times, which happened 200 years ago. However, none of these happened uniformly across India. India is a very large subcontinent. Hinduism did not appear fully formed across the subcontinent, one fine day, like Draupadi appearing fully formed from the sacrificial fire.
We know that the Rig Veda, in its current form, was consolidated in the Kuru-Panchala region around Haryana about 3,000 years ago. The Upanishads evolved 2,500 years ago in the eastern Gangetic plains in what is today Bihar. The early Dharma Shastras, which are over 2,000 years old, refers only to North India as Aryavarta. Manusmriti, which is less than 2,000 years old, refers to the entire subcontinent, from the Himalayas right up to the coasts, as Aryavarta. Tamil Sangam literature is aware of the North, and refers to Aryas as a people different from the Cheras, Pandyas and Cholas, who are referred to for the first time in Ashokan edicts 2,300 years ago.
We know that Brahmins started receiving land grants from around 1,500 years ago and that led to the construction of temples especially in the South. The earliest instance of land being given to Brahmins is in the 3rd and 4th century in Andhra Pradesh; the 4th and 5th century in Odisha and Gujarat; the 6th and 7th century in Karnataka and Tamil Nadu and the 8th and 9th century in Kerala. Thus, we see the gradual spread of Brahmanism from North India to the South. This is collaborated by mythologies of sages like Agastya. It is said he travelled from the North to the South. He carried with him mountains and rivers from the north to create the mountains and rivers of the south. Thus Brahmanism carries its geography from the north to the south and starts referring to southern rivers as Dakshin Ganga and southern cities as Dakshin Kashi.