Torana Definition: The word 'torana' is from the Sanskrit language and is used commonly as the term to describe the stylized decorative framework surrounding sculptural and painted figures in Indian art specifically and Asian art in general. A torana can be described as a gate, gateway, arch, throne-back, backrest, or decorative niche surrounding a deity, god, buddha, bodhisattva or religious hierarch, teacher or saint. A decorative torana can also be employed above a temple doorway or decorating temple windows as found in the Kathmandu Valley of Nepal.The Torana in Indian & Early Tibetan Art
Examples of the decorative Indian toranas from the various regions and time periods show that there was no standard way of depiction. The ornamentation was expressed differently in different regions and times. There was however a certain basic model for the torana that developed and disseminated into the Himalayan regions. The most basic form was a recessed niche and a simple arch over a central figure. In later Indian models the torana became more integrated with the foundational supports of a sculpture, i.e. the throne and lotus seat of a figure.
The word torana has come to be used in referring to a number of different things. In the past the arch was either above the figure only or extending down from the over-head arch to the base on both sides of the figure. However, there are actually three parts that make up the visual object of the torana: the  arch above, the  side supports and the  foundation (throne, lotus). Later Indian and Nepalese depictions often include pillars for supporting the arch. In later Tibetan depictions the pillars are gradually removed and replaced by the 'six ornament' designed arch (torana).
Early examples of Tibetan torana, generally referred to literally as a 'throne-back' (Tibetan: gyab yol) appear purely artistic following the simple and varied models seen in India, Kashmir and Nepal. Side pillars were common and depictions of various kinds of birds and animals are found placed on the tops of the pillars. The actual arch can be formed as a stylized cave of multi-coloured rocks, an architectural form, or intricate vine work designs.
Depictions of early toranas showing an elephant on either side of a central figure with a sharabha above, and a makara above that, are found as early as the 12th century. Sometimes a boy is depicted atop the sharabha. Sometimes the makara is replaced by a goose. Again at other times a gurada - king of birds - is placed at the top center. There is a tremendous amount of variation. Some examples are very complex while others are very simple and plain in design. The Torana in Later Tibetan & Himalayan Buddhist Art
In later Tibetan and Himalayan Buddhism, possibly developing in the 17th century, the ornately displayed throne-back, Torana, becomes known as the 'six ornament' design. The general shape is like an oval gate or frame, sometimes rectangular. On each side of the torana, at the bottom left and right are elephants. Supported above that are lions (or snow lions), a horse (often with the characteristics of other animals such as a lion, etc.). Above that is a small boy who sometimes holds a conch shell in one hand and supports a horizontal throne strut with the other. Above that is a makara (water creature). Above that is a naga - with a human upper torso and snake's tail for the bottom which sometimes extends upward. At the very top is a single garuda bird who is sometimes shown biting down with the beak on the two extended tails of either the two makarsa or the two nagas from below. Sometimes the nagas are depicted biting down on snakes held in outstretched arms.
Also there can be an ornate silk canopy above the torana. It is not clear how the various elements of the torana are enumerated into the group of the 'six ornaments.' It is possible that the boy and the flying horse are grouped as one ornament. Regardless, the 'six ornament' design appears to be a late development of the torana in Tibet and is found primarily from the 17th century onward.
Symbolically the 'six ornaments' have many meanings such "as the seven things to be eliminated on the path, the six perfections, the four gathering things, the strength of the ten powers, the stainless and the clear light." (Gateway to the Temple by Thubten Legshay Gyatsho. 1971, 1979. page 46).The Torana in Bon Religious Art
In the Bon Religion there is also a unique throne back (Tibetan: gyab yol) which is described for the special figure of Nampar Gyalwa a form of Tonpa Shenrab, founder of the Bon religion. This throne back is different from the Buddhist description most notably because in the Bon depiction the lion at the bottom of the throne back is eating a human figure and above that the winged-lion-horse (dragon) is eating a serpent spirit (lu). Although specific to the biography of Nampar Gyalwa this throne back is also commonly found with the Four Transcendent Lords and used in both painting and sculpture.
According to the biographical literature the animals should be a lion, dragon and water monster. This is described in detail in the story of Nampar Gyalwa found in chapter 50 of the Ziji a twelve volume biography of Tonpa Shenrab.
The images below show two paintings of Shakyamuni Buddha with relatively clear depictions of the torana followed by numerous images of torana fragments.