Some might say that they could ask for help from the Taixu Devil Race of the Great Snow Mountain.
But it's important to understand that the Devil Race itself is divided into factions!
Take the Devil Race from the Great Void Province for example, though they too are a branch of the Great Snow Mountain Devil Race and revere the Demon King, they have their own ulterior motives.
Originally, they had a complete fallout with other factions of the Devil Race in order to monopolize the Taixu Secret Realm. Perhaps when facing encirclement by the human race, they might extend help without hesitation out of a sense of shared fate or a fear of mutual destruction.
But under the current circumstances, they would definitely choose to sit on the fence unless the Taixu Devil Race was willing to pay a price, and even then, they would have to endure being exploited in their moment of weakness.
