Please note that Mommsen uses the AUC chronology (Ab Urbe Condita), i.e. from the founding of the City of Rome. You can use this reference table to have the B.C. dates
From: The History of Rome, by Theodor Mommsen
Translated with the sanction of the author by William Purdie Dickson
War in the Desert - Mauretanian Complications
When Metellus again took the field in 647, Jugurtha nowhere held his ground against him; he appeared now at one point, now at another far distant; it seemed as if they would as easily get the better of the lions as of these horsemen of the desert. A battle was fought, a victory was won; but it was difficult to say what had been gained by the victory.
The king had vanished out of sight in the distance. In the interior of the modern beylik of Tunis, close on the edge of the great desert, there lay on an oasis provided with springs the strong place Thala;(14) thither Jugurtha had retired with his children, his treasures, and the flower of his troops, there to await better times.
14. The locality has not been discovered. The earlier supposition that Thelepte (near Feriana, to the northward of Capsa) was meant, is arbitrary; and the identification with a locality still at the present day named Thala to the east of Capsa is not duly made out.
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Reference address : https://www.ellopos.net/elpenor/rome/4-04-rule-restoration.asp?pg=49