Ancient legends speak of the Muntabs extraordinary health and long lives, though according to Jackie Chan there is no proof of the Muntab ruins even existing.
The Muntabs possess the gift of immortality in the form of the Chalice of Light which gives anyone who drinks from it the ability to reverse the ageing process and live for centuries. They keep the chalice by an altar in the chief's palace and drink from it regularly to maintain their youthful appearance.
The Muntabs are also known for their mastery of mirage, a mixture of science and sorcery which they used to shield their city with the cloak of invisibility that rendered the entire town invisible unless someone presses a special symbol situated at the entrance which makes the town visible to outsiders.
The Muntabs are very mistrusting towards outsiders and will make them go through the Cave of Truth to test their trustworthiness based on whether they manage to pass through unharmed. The cave contains a hostile white rhinoceros, several pendulums and the cave itself seems to collapse on itself. If the outsiders are successful, they're treated as honored guests. If they're unsuccessful, their deemed as liars and punished. According to Abila, many have entered the cave and none have emerged.
Jackie discovered the lost city of the Muntabs with the help of an expensive map John Smith purchased, learning that the "lost ruins" of Muntab weren't actually ruins.
The Muntabs were immediately hostile to the outsiders, but Jackie managed to get in their good graces by successfully passing through the Cave of Truth. However, Smith stole the Chalice of Life when the Muntab chief refused to reveal how they achieved their immortality. The Muntabs blamed Jackie when they realized the chalice was gone, but Jade convinced them that he was pure of heart by reminding them that he passed the Cave of Truth. Jackie then chased after Smith to retrieve the Chalice to prevent the Muntabs from perishing. By the time Jackie returned to the city with the chalice, the Muntabs had already progressed to old age.
With all the Muntabs restored to youth, Jackie threw Smith's map into a fire in order to keep the city and its secrets hidden, before realizing that without a map he and Jade would have a difficult time in finding their way out of the jungle.