The phrase "an ancient system of" is correct and usable in written English.
It can be used when referring to a historical or traditional method, practice, or structure that has been in existence for a long time.
Example: "The researchers studied an ancient system of irrigation that has been used for centuries in this region."
Alternatives: "a historical method of" or "a traditional practice of".
Mathematics- Research an ancient system of mathematics.
They can rate their friends, relying on an ancient system of hieroglyphs — smiley faces, ice cubes, and hearts, which stand, respectively, for trustworthiness, coolness, and sexiness.
The mountains and plains alike are also latticed with karezi, an ancient system of irrigation tunnels, some dipping as much as 100 feet below the surface.
I am guided through their familiar landscape by an ancient system of strips of paper, Post-Its, pencil markings and crisp corner-turnings, identifying landmarks and little phrases.
Here, you can dine next to the sea from which your meal was hauled just hours before by an ancient system of nets, pulleys and winches.
But these days "most scholars accept that Bach shared other baroque artists' passion for gematria", an ancient system of assigning numerical values to words or phrases.
The TLRs are part of an ancient system for protection against microbes and evolved in animals well before viviparity (7).
The complement system is built upon an evolutionarily ancient system of innate immunity, providing the first line of defense in recognition and clearance of non-self invaders.
In an instant, the City of London went from a charming, ancient system of legally protected, relatively small institutions to electronic banking, enormous investment conglomerates and millionaires who made their money via speculative bets.
Discovered by scientists only a few years ago, CRISPRs are elements of an ancient system that protects bacteria and other single-celled organisms from viruses, acquiring immunity to them by incorporating genetic elements from the virus invaders.
T3SS is also an ancient system and clearly predates the origin of the mitochondria from prokaryote endosymbiosis [69], [70].
