The story of jeans is the story of ‘cloth’ itself. The origin of the word comes from Genoa which is one of the claimants for the post of the inventor of this cloth. Gênes as it is known in French is what seems to have given us Jeans. But another city Nîmes also claims to be the inventor. This fabric which came ‘from Nîmes’ or ‘de Nîmes’ in French gives us denim.
The fabric that gave us Jeans came from a place called Al-Fustāt in 220 AD. This place today is known as Cairo. The fabric made in the city was known as Fustian which was a heavy cloth woven from cotton.
Before the Industrial Revolution, weaving was perhaps the most time-consuming of all activities known to man. It would take a man-month to produce enough fabric to make a dress and a man-year of work to produce enough cloth for a sail. The image of an industrious woman during the Middle Ages was one of a woman spinning thread precisely for this reason.
Source: Wikipedia
A heavy cotton cloth that was hard to damage would have been highly valued at such times. With the rise of Islam, the fabric found its way to Europe. Al-Andalus or Andalusia which covered most of modern Spain was under the Umayyad Caliphate. This brought the fabric to the European mainland and it spread across the Mediterranean as a popular material.
Woad died fustians which were blue became popular in Chieri and Milan. In Genoa, sailors started preferring this material for making sails as well as garments due to their rugged nature and ability to last long.
And thus the fustian fabric completed its long journey towards becoming Jeans.
In England, it was not until the 16th century that the words Geanes, jeanes or jeans could be found. From Genoa, the fabric found its way to Lancashire and the factories in the cities started churning out blue fustian fabric that came to be known as Jeans.
In the 17th century, the fabric from Lancashire found its way to America which at the time was still being settled and did not have much production capacity for most goods.
It would be more than two centuries before Levi Strauss and Co. started producing denim pants in the US. In 1873 Levi Strauss and Jacob Davis patented their riveted work pants.