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agatch

Among the Turcomen, 19ᵗʰ century, a unit of distance equal to that covered by a horse and rider in one hour, about 5 miles.

This is the Turkish ağaç.

source

In regard to distance, the Turcoman's computation is equally unsatisfactory. From the Persians, and through the Koran, they have learned the word saahat (an hour), but they have not the faintest idea of what an hour means. They will talk to you about 'an hour's journey,' but in all likelihood it will prove to be three hours' journey. Their computation depends upon the distance which an ordinary horse can travel, at his usual pace, in the course of a day. They will tell the traveller that the distance from one place to another is bir gidgé (one day's journey), or yarum gidgé, (a half-day's journey), cherick gidgé (a quarter of a day's journey). When the distance is less than the latter they will say that the place is not far off. They have a measure which is called an agatch. This is supposed to correspond with the Persian farsang, which conveys the idea of an hour's swift walking—about four miles. A Turcoman agatch means an hour's riding, for no one walks in their country. As a rule it means about five miles, for a Turcoman horse, even when walking, will cover that distance in an hour. Literally, agatch is a piece of wood. I suppose that the name is derived from the custom of placing poles along the road, to mark the distance, just as in Russia we find the blue-and-white striped posts which indicate the versts.

Edmund O'Donovan.
The Merv Oasis. Travels and Adventures East of the Caspian during the Years 1879-80-81 including Five Months' Residence among the Tekkes of Merv.
London: Smith, Elder, & Co., 1882.
Vol. II, page 418.