The Green Fire Island was located northwest of the main Vast Expanse Dao Palace island. It was surrounded by seven to eight smaller islands and could be considered a greater island in the region. A spirit meridian rested within the island. In addition, it produced Green Fire Grass. That was why it counted itself as one of the top twenty out of hundreds of outer islands belonging to the Vast Expanse Dao Palace.
The top ten islands were run by the Vast Expanse Dao Palace's Nascent Soul realm cultivators. The remaining islands, like the Green Fire Island, were mostly run by the three Elders as well as disciples of Nascent Soul realm cultivators. None would easily allow others to intrude into their territories.
This was why when Feng Qiuran proposed to allow Wang Baole monopoly over the Green Fire Island resources, that her proposal had been met with Mie Liezi's vehement opposition. They finally came to a compromise to allow Wang Baole and Liang Long to share the island.