The Celts as a people can be defined as those who lived in a broad band beginning in Central Europe and stretching in an arc toward the west then north into Britain and Ireland. They shared common religious beliefs, customs, language and art, but existed as separate groups governed by their own local chieftains or Kings. It is believed that Celtic settlement of Britain occurred at two different times; the first from France and Germany in about 2000 BC, the second from Roman Gaul (France) in about 200 BC.

By 100 BC the Celts and their art on continental Europe had waned, while in Britain Celtic Art survived until about AD 150. The main forms of Celtic Art survived even later in Ireland and Scotland, which were not conquered by the Romans.

Celtic art emerged in the geometric patterning of an early Iron Age culture known as the Hallstatt Culture. Characteristic Celtic traits are later found in the La Tène Culture which succeeded the Hallstatt and lasted from 450 BC to 50 BC. This period is named for the La Tene valley in Switzerland where a large amount of early Celtic artifacts were found. These artifacts were patterned with intricate spirals and interlace with bronze metalwork helmets, shields and jewelry covered in stylized animal and vegetable forms.

The spiral is among the most ancient symbols in Celtic art and has been carved into standing stones since late Stone Age times. At the burial site at Newgrange in Ireland, which dates to about 3000 BC, spirals are found singly or in pairs. Also, the only known example of a triskele or threefold arrangement is found on the stones of Newgrange.

The Celts incorporated intricate patterns into their designs - key patterns are named for their key-shaped paths, and are based on spirals. They are constructed on a diagonal grid, and bend back upon themselves at various angles forming the small triangles of dark background. This gives key patterns their distinctive look. They are usually drawn or carved within rectangular borders, but the Celts fit them into circles, triangles or panels.

The Celts were a pastoral and agricultural people, living in harmony with the land and the seasonal cycles. They were Druids who believed that all things in Nature are connected and interdependent. This belief was reflected in their art in which stylized animals intertwined in complex, unbroken knots, without beginning or end.

The Celtic people believed strongly in the power of animal symbolism and the most frequently used animal symbols of the boar, fish, serpent, bird, and herd animals represented fertility and vitality. The Celts incorporated these animals stylistically into their jewelry and personal belongings believing that the strengths of these animals would be granted to the wearer.

St. Patrick’s arrival in the 5th century brought a full-scale conversion to Christianity throughout Celtic Ireland and monasteries became the principal artistic centers. Christian Celtic art consisted mainly of stone crosses, illuminated manuscripts, and metal objects such as chalices, shrines, and reliquaries. Because religious artwork featuring animals was considered pagan by early missionaries, Celtic art developed from its concentration on animal designs into the simplified knotwork that defines it today.