Newar paintings, called “paubha” in Newari and “pata” in Sanskrit, are usually rectangular in shape and are prepared from cotton woven specially to fit the dimensions required  for each painting. Unlike the Tibetan thanka, the Newar Paubha is mostly uniform in size. Tibetans may craft huge s for ceremonial display, as seen is Tashilhumpo monastery or Jokhang Temple, Tibet, or on Paro, Bhutan.

With regard to subject matter, paubhas usually portray figures of important divinities, mandalas of divinities, and monuments surrounded by various figures. These paintings are mostly created for religious purposes. They were used as aids to meditation. In the early days of paubha painting, both patrons and artists were motivated by spiritual concerns. Newar Buddhists commissioned paubha paintings in order to earn merit, and they were displayed on special occasions. The paintings, which serve as aids in meditation, were hung on private altars, in temples and in monasteries. For instance, a large Paubha, dedicated to Maha Manjushri, was once hung on the walls of Hiranyavarna Mahavihara. In the present day, this tradition of displaying Paubhas is now endangered due to the rise of theft, pollution, and commercialization.
          
It is difficult to determine when and where Paubha paintings originated, owing to the lack of early Paubha paintings in Nepal. Lain Singh Bangdel, the veteran authority on Nepalese art, confidently states that Newar artists were the pioneers of Paubha painting. Through an analysis of the historical development of relations between Nepal and Tibet, we find evidence to support his statement.

Most early thanka paintings from Tibet appear to have been strongly influenced by the Nepalese style, resembling painting styles such as those found in the Astasahasrika Prajnaparamita Maanuscript.

The Newar tradition of displaying Paubhas, mentioned earlier, takes place over several days during the Bahidyo Boyegu Ceremony, held in the month of July-August. During this period, Several Viharas of Baha or Bahis in Kathmandu and Lalitpur display their paubhas for communal worship. But in recent times, the threat of theft and art trafficking has made the owners of these paubhas hesitant to display them. The result is that the display tradition has been discontinued in most viharas. Here are some examples of Paubha formerly displayed in Patan and Kathamandu.

1.Suraschandra Mahavihara-Nhayakan Bahi- Paubha depicting Shilu Tirtha
2.Hiranyavarna Mahavihara-Kwabahal- A Grand Paubha depicting Manju Vajra
3.Gopichandravihara-Patan Paubha depicting Sakyamuni with host of bhikshus,yaksha,gandharvas,
kinnars and so forth paying homage, 1437 A.D.
4.do    Vanaratna’s wife distributing alms (1469)
4.Jesthavarna Mahavihara-Patan Paubha depiting Dearath, Bhimrath, and Maharath
5.do    Astamatrikas and Astadikpalas
6.do    Viharalaksana chitra dated 1344A.D.
7.Tanga Baha –Patan  Yamadvara laksana
8.Vikramashila vihara   Paubhas depicting Sristikarta Lokeshvara dated 1819A.D.

Nowadays, since Tibetan Thangka painting has become very popular in the world market; when people speak of Thangka, tibetan Thangkas are what they have in mind.

The casual visitor knows nothing about Newar painting and its characteristic features, and about the uniquenes of these early Newar paintings. Knowings the importance and features of Newar painting it has become essential for these Nepalese artists wishing to preserve Newar painting as a separate style. Although in its early stages Tibetan Thangka painting was highly influenced by Nepalese style, after the sixteenth century, marked difference between the two styles.

Reference: 

Sacred Art of Nepal, Nepalese Pauba Paintings Past and Prestent, Handicraft Association of Nepal, Kathmandu, Nepal