According to Hindu mythology Kubera was the son of a sage called Vishravas, hence his he is also called Vaishravana or Vishravana. It is said that Kubera performed austerities for a thousand years, Lord Brahma then in reward gave him immortality and made him god of Wealth, guardian of all treasures of earth, which he was to give out to whom they were destined. The abode of Kubera was Kailash, when Brahma appointed him God of Wealth, he gave him Lanka as his capital and presented him Pushpaka Vimana which was of immense in size and moved at the owner's will at marvelous speed. Later on Kubera's brother Ravana seized Lanka and Pushpaka Vimana from him. Kubera then made his abode in mount of Kailash in Himalaya
He has both Yi-dam and Dharmapala forms of great antiquity in India and Nepal .As Yi-dam he is called Jambhala, probably from the jambhara (citron); in this form he always carries citron in his right hand. In Tibet Kubera or Vaishravana has been one of the primary protectors of the Gelugpa sect since the fourteenth century. He has two main aspects, that of a warrior protector and that of deity of wealth.
As mentioned above, he is one of the Lokapalas,guardians of Mount Sumeru, centre of Universe; as well as one of the Regents of the Four Cardinal Points. As a guardian of the North he is called Vaishravana by Buddhists, and his abode is Alaka in the Himalayas, abounding in wealth and magnificence, where he is attended by Yakshas and horse-headed men called kinnaras. It is believed that performing prosperity rituals to Kubera or Jambhala will increase wealth and prosperity. There is a special ceremony in Tibet for imploring Kubera for riches, which is called Yanyung. Kubera is popular in Tibet, Mongolia, China, Nepal and in Japan where he is known as Bishamon. There are many temples of Bishamon in Japan and he is popularly worshiped by Japanese Buddhists.
Iconographically there are many forms of Kubera, the present one he has been depicted as the god of wealth and his shakti is Vasudhara. As a god of wealth, he generally holds a jewel and mongoose. When Kubera presses the two sides of the mongoose it vomits the treasures within. In Tantra he plays an important part. The tantra of Vaishravana as god of wealth was taught by Shakyamuni Buddha. It was translated into Tibetan language in the eleventh century by Zangkar Lotsawa who came from Zangkar in West Tibet. In the thirteenth century, the teachings passed to the noted scholar Buton Rinchen Gyaltsan, on this the history of Vaishravana is based.
In popular Buddhism also the cult of Kubera or Vaishravana is very popular, devotees made their purses and bags in the shape of Nakula (mongoose) in believe that their bags or purses will be always full of wealth.
The pot-bellied Kubera is depicted here seated on an angry snow lion on lotus base against the wisdom fire aureole. He is wrathful in appearance and his right hand is in threatening-gesture, while his left hand holds a jewel-spitting Nakula or mongoose. He has bulging eyes, blazing eyebrows, moustache and three beards. The hair of Kubera is upswept in a stylized knot with decoration on it. He wears gold crown and ornaments with jewels, flowing silk scarf, sacred-thread, dhoti and strong boots. This fine sculpture is very much suitable for altar for the practice and ritual of Kubera, lord of treasures.
This description is by Dr. Shailendra K. Verma, whose Doctorate thesis is on “Emergence and Evolution of the Buddha Image (From its inception to 8th century A.D.)”.