The history of soap stretches back thousands of years, with the earliest recorded soap-making dating to around 2800 BCE. Ancient Babylonians produced a basic soap by boiling fats with wood ash. This early soap was used primarily for cleaning wool and cotton for garments, as well as for medicinal skin treatments rather than bathing.

Babylon, located near present-day Baghdad, grew from a small port on the Euphrates River into one of the largest cities of the ancient world, playing a central role in early technological innovation.

Around 1550 BCE, the Egyptian Ebers Papyrus records the production of soap-like substances made from animal and vegetable oils combined with alkaline salts. The Phoenicians later used rendered goat tallow mixed with wood ash around 600 BCE, and soap became widely used by the Romans.

The Celts referred to soap as saipo, which may be one origin of the modern word “soap.” Another theory links the name to Mount Sapo in Rome, or to sapo, a clay-like substance used for cleansing.

Roman legend tells of women washing utensils in the River Tiber at the base of Mount Sapo, where animal sacrifices were performed. Rainwater carried animal fats and wood ash into the river, creating a natural cleansing mixture that lifted grease and dirt.

For thousands of years, soap-making remained largely unchanged, relying on natural fats and oils from animals and plants. It was only in recent centuries that soap became widely used for personal hygiene.

Following World War I, shortages of fats and oils led to the development of synthetic soaps and detergents, which were mass-produced and marketed. Today, many commercially branded “soaps” are actually synthetic detergents that can strip the skin of its natural oils and contribute to irritation.

As a result, there is growing demand for naturally based soaps that avoid petrochemical additives and support healthy skin function.

Saponins: Nature’s Soap

As a natural alternative to animal fats, many plants contain compounds called saponins (from the Latin sapo, meaning soap). Saponins have both lipophilic (oil-attracting) and hydrophilic (water-attracting) properties, allowing them to create foam and act as natural surfactants.

Surfactants break the surface tension of water, lifting oils and grime from the skin so they can be rinsed away. Plants containing saponins are found throughout the world and have been used for centuries as natural cleansers.

Kūmarahou: Aotearoa’s Native Soap Plant

In Aotearoa New Zealand, we are fortunate to have the native kūmarahou bush, which contains exceptionally high levels of natural saponins. These compounds form the basis of our gentle, healing Aotea Kūmarahou soap.

The kūmarahou bush produces masses of yellow flowers in late spring. When the flowers are crushed and mixed with water, they create a natural foamy lather.

Kūmarahou was historically known as “gum digger’s soap”. Bushmen discovered that washing their hands in a stream while rubbing kūmarahou flowers effectively removed sticky kauri gum, oil, and dirt without harsh abrasion.

This knowledge was learned from local Māori, who had used kūmarahou for centuries as a gentle natural cleanser and in traditional rongoā Māori. Kūmarahou was used topically for healing skin infections and inflammation, and internally as a tonic for respiratory complaints, rheumatism, and gout.

Soap Plants Around the World

In other parts of the world, plants commonly known as soapberries — a family of around 12 species — have been used for thousands of years as natural soaps. These shrubs and trees are native to tropical and subtropical regions of Asia, the Americas, and parts of the Pacific.

Even today, soapberries are used as gentle natural soaps and laundry detergents, valued as alternatives to synthetic products containing dyes, fragrances, and chemical additives.

Shop our Kūmarahou range →