Question

What was the extent of india according to Vishnu Purana?

Answer 1

According to Vishnu Puran, Vishnu created Shiva and according to Shiva Purana it's vice versa. In Devi Bhagavata Purana, the supreme goddess created Vishnu and Shiva. 
//Shiva-Purana says Shiva created Vishnu,//

//Devi-Bhagvatam says Devi Created Rudra and Vishnu. //

//Vishnu Purana says Vishnu Created Shiva.//

Confusion is just because we can't grasp the esoteric Knowledge of Purana. Now Let's analyze it through Vedas.

Shiva -Purana says Shiva Created Vishnu, same is mentioned in Vedas.

Answer 2

The 'Vishnu Purana' (IAST: Viṣṇu Purāṇa) is one of the eighteen Mahapuranas, a genre of ancient and medieval texts of Hinduism.[1] It is an important Pancharatra text in the Vaishnavism literature corpus.[1][2]

The manuscripts of Vishnu Purana have survived into the modern era in many versions.[3][4][5] More than any other major Purana, the Vishnu Purana presents its contents in Pancalaksana format – Sarga (cosmogony), Pratisarga (cosmology), Vamśa (mythical genealogy of the gods, sages and kings), Manvañtara (cosmic cycles), and Vamśānucaritam (legends during the times of various kings).[6][7][8] Some manuscripts of the text are notable for not including sections found in other major Puranas, such as those on Mahatmyas and tour guides on pilgrimage,[9] but some versions include chapters on temples and travel guides to sacred pilgrimage sites.[1][10] The text is also notable as the earliest Purana to have been translated and published in 1864 CE by HH Wilson, based on manuscripts then available, setting the presumptions and premises about what Puranas may have been.