The Avalokitesvara is seated in lalitasana, the posture of royal ease, on a double lotus base. His left arm supporting the weight of his torso, his right hand draped over his right knee. His left hand rests on the edge of the pedestal holding a stem crowned with lotus flower above his left shoulder. He wears pendent earrings, floral shaped arm bands, bracelets, necklace and decorative hair band. He wears a upavita (sacred thread) diagonally across his chest. The Avalokitesvara also wears a patterned long skirt tighten to his waist. His hair runs down his shoulder in the back and also with a couple of braided hairs hanging over the shoulders on both sides. His face is peaceful with serene expression.
The pose with an arm resting on a raised knee is especially seen in Chinese Buddhist art, for bodhisattva images, but is found in Indian art from at least the 8th century, with one famous example from the Ajanta Caves (the Naga-king illustrated below) probably dating to around 478. It became associated in China with Guanyin from the late 9th century.
The statue is likely made in 9-10th century Southeast Asia, most probably from Java Island, in Srivijaya period and considered as a rare piece.
Reference:
https://www.rijksmuseum.nl/en/collection/AK-MAK-389