Which came first, the chicken or the egg, asks a famous riddle. After all, the primary source of chicken eggs are chickens, and the primary source of chickens are those same eggs. To a casual observer, this would seem to be an endless regress, hence the question. The egg came first, and was first laid in India.
In the jungles of Thailand, Cambodia, and Burma lives an animal called the Red Junglefowl. It is a tree dwelling bird, distantly related to the Pheasants that European aristocracy hunted for sport. Animal traders brought captured birds to India, where it was hybridized with the Grey Junglefowl, producing the modern chicken. The ancient Indian birdkeepers noted that the birds were easily cared for, enjoyed eating insects (and so were very useful to farmers), and were delicious with the right spices. Over time, Indians lost interest in eating the eggs, but those not prohibited from eating meat for religious reasons continue to enjoy eating the chickens themselves.
Over the years, the chicken was spread by trade through Persia, eventually reaching Greece and Europe. The ancient Greeks and even Romans thought of the chicken as a very exotic bird, as their only supply was through the Persians, and relations between the Greek city-states and the Persian empire were often frosty. However, centuries of trade quickly populated the bird throughout Europe.
Colonists to "The new world" of North and South America often brought domestic animals with them, and the expansion of the chicken eventually reached the Pacific Islands in the 1800s. Chickens are now found worldwide except Antarctica (where they occasionally arrive dead in the form of food).