In Buddhism, Maitreya is a bodhisattva, who is the successor to the present Buddha Gautama, and will appear on Earth in the future. This time will come when most of the terrestrial world have forgotten dharma: Maitreya, having achieved complete enlightenment, will then teach the pure dharma.
To discover more about Gandharan Buddahs, please visit our relevant blog post: Understanding Gandharan Buddha Poses and Postures.