An excavation of ancient Babylon revealed evidence that Babylonians were making soap around 2800 B.C. Babylonians were the first to master the art of soap making. They made soap from fats boiled with ashes. Soap was used in cleaning wool and cotton, in textile manufacture and also medicinally for at least 5000 years.
The ancient Egyptians mixed animal and vegetable oils with alkaline salts to produce a soap-like substance. The Phoenicians used goat's tallow and wood ashes to create soap in 600 BC. Early Romans made soaps in the first century A.D. from urine and soap was widely known in the Roman Empire.
Roman legend has it that soap got its name from Mount Sapo where animals were sacred and the residual mixture of the sacrificial animal fat, wood ashes and rainwater flowed down to the Tiber River where the peasant women washed their clothes. They discovered that the soapy mixture from the fats and wool ashes made their clothes cleaner with less effort.
Ancient Romans became obsessed with bathing and had many public baths.
Soap making was established as a craft in Europe around the 7th century. Italy, France and Spain were early soap manufacturing centres due to the readily available supply of olive oil- very popular for making high quality soaps. The natural Savon de Marseille became the most popular soap in France; it contained a blend of coconut, palm and 72% pure olive oil. In 1688 Louis XIV decreed a law banning the use of fragrances, animal fats and colour in the manufacture of Savon de Marseille.
The "technology" of soap making was exclusive to small guilds of soap makers. The demand was high but the price was pretty high too especially as the guilds had the monopoly to produce soap. The soap making industry became very lucrative and heavily taxed too, so it prevented poorer people from buying it.
Eventually the soap making became so heavily regulated by the authorities, it became difficult for the soap makers to conduct their business or have access to essential supplies. As a result soap makers learned to use a variety of oils to make their products. Modern soap making benefits from this today as high quality soaps are often made using several types of oils and fats, each with its own unique characteristics.
Commercial soap making really took off in the middle of the 19th century making it an affordable commodity.
But the chemistry of soap manufacturing changed significantly in 1916 when the first synthetic detergent was developed in Germany in response to the shortage of fats during World War I.
Most soaps on the market today are not true soaps by definition. Compositionally they are closer to washing detergents. Although modern chemistry has refined the raw materials and the techniques, soap making is fundamentally the same as it was thousand years ago.