Walnut Trees have been around for thousands of years!

The walnut tree has thrived since before recorded history. It is said to be one of the world's oldest source of edible nuts.

Archeological remains of walnuts have been found as far eastward as the Himalayas and to the distant west and northwest of Persia (Iraq) as well as in Turkey, Italy, France, hte USA and Switzerland. The oldest archeological site where walnuts were unearthed is in the Shanidar caves in northern Iraq. Evidence of walnuts was discovered in a Mesolithic dunghill in Switzerland. During the Neolithic period (about 8000 BCE to 2000 BCE) items found in Switzerland's lake district included walnuts and petrified roasted walnut shells were found in Perigord, France.
In ancient Persia, only royalty could eat the fruit referred to as the Royal Walnut. Iraq (known as Mesopotamia in the history books) boasted walnut groves in the famed Hanging Gardens of Babylon about 2,000 BCE. The Chaldeans left clay tablet inscriptions that accounted for these orchards. These inscriptions are the earliest surviving written records mentioning walnuts. About 1795 BCE, Hammurabi, the 6th king of the 1st dynasty of Babylon ( the ruins of Babylon are about 80km south of Baghdad (set down a code of laws which mentioned walnuts in the section governing food.
In the Old Testament King Solomon is quoted: "I went down into the garden of nuts to see the fruit of the valley." These words are said by some to refer to flourishing walnut groves. However, the likelihood of these nuts being other than almonds is very remote because of the almond nut image that was used as symbols commonly in Hebrew icons and stone carving displays in Jerusalem inside Solomon’s temple.  The adaptability of almonds is such that it is much more likely for almond trees to succeed than walnut trees in the climate and soils of Israel.
Although the first cultivation of walnuts is attributed to the ancient Greeks, it may well have been the Persians who first cultivated a superior variety. When the Greeks encountered Persian walnuts (larger and better than theirs) they began to improve their variety by cultivation. The ancient Greeks also used walnuts as a medicine and as a dye for hair, wool, and cloth. The walnut appears in Greek mythology in the story of Carya, with whom the god Dionysus fell in love. When she died, Dionysus transformed her into a walnut tree. The goddess Artemis carried the news to Carya's father and commanded that a temple be built in her memory. Its columns, sculpted in wood in the form of young women, were called catyatides, or nymphs of the walnut tree.
Among the more unusual uses of walnuts the the Egyptians used walnut oil to embalm mummies by replacing the blood with walnut oil.
About one hundred years after the Greeks were commonly using walnuts, the Romans discovered their merits and were willing to pay dearly for the luxury of serving them along with fruits for dessert. In the ruins of Pompeii whole, unshelled walnuts were among the foods on the table at the Temple of Isis on that fateful day (24 August 79 BCE) when Mount Vesuvius erupted.
Walnuts may have journeyed from Kashmir to China during the Han dynasty, some time between 206 BCE and 220 CE. Since trading existed long before written records, merchants, explorers, and conquerors were credited with bringing the walnut from the Mediterranean into Europe, possibly during the third century BCE. Some historians question this theory because of archeological evidence discovered in Switzerland. It is possible that during the last Glacial Period walnut trees disappeared from the frozen earth of the Northern European countries and that the barbarian invaders and Greek and Roman conquerors brought the trees back to Europe. The very name of the walnut tree and its nut comes down to us from the Romans. Juglans regia (walnut tree) and nux juglandes (the walnut) stem from Jovis Glans or the Royal Nut of Jove. The word for nut itself derives from the Latin nux or nucleus (fruit of the shell), with a suggested derivation from nox (night) owing to the dark juice of the husk of the walnut, which was used to dye wool.
The first mention of the walnut's arrival in the British Isles appeared in the Encyclopaedia Britannica dated 1567. However, walnuts were only acceptable served at the end of a meal along with port and Stilton cheese. English merchant sailors transported walnuts across the globe during Medieval times. Walnuts became so associated with the English that they were often called English walnuts. However they didn't really penetrate the English soul until after World War I when they became a commercial enterprise.Unlike the English the French embraced the walnut. Cultivation began during the fourth century. Charlemagne, eighth to ninth century, ordered his gardeners to plant walnut trees on his extensive properties. Walnuts were so highly regarded that during the eleventh century, French peasants were expected to tithe walnuts to the church. From Medieval times until the end of the 18th century, Europeans were blanching, crushing, and soaking walnuts and almonds to create a rich, nutritious milk, a common household staple. While the poor dined on the wild walnuts, the rich were able to afford the larger, more expensive, cultivated variety. In the French countryside, it was tradition to hang a bag of walnuts from the ceiling beam in the kitchen to represent abundance. Walnuts also represented longevity. Some young men believed the walnut tree to possessed aphrodisiac powers and attempted to sneak a leaf into the shoe of a young woman they admired. Toward the end of the 17th century, walnuts along with chestnuts became important staples in France. During the famine of 1663 the poor consumed their walnuts and then resorted to grinding up the shells along with acorns to create coarse, unpalatable bread (Wellwood walnut flour is not made from ground walnut shell). In World War II starving families living in the small villages of the Perigord district turned to their walnut groves for a source of protein.
The upper Great Lakes region of the USA provides archeological evidence of walnut consumption dating back to 2000 BCE. Native American Indians enjoyed the pleasures and health benefits of the black walnut well before European explorers arrived. Along with eating the walnut itself, the Indians used the sap of the walnut tree in their food preparation. The first European walnuts to arrive in the United States came from Spain in the early 1800's, with the French contributing many of their varieties during the latter part of the nineteenth century.
Nowadays commercial quantities of walnuts are grown in the USA, France, China, Russia, India. Turkey, Greece, Italy, the Czech Republic, Hungary, Switzerland, and Australia and New Zealand.