Justin, Philippic Histories 1.1:
In the beginning of the world, the power of tribes and nations lay with kings, because it was not popular canvassing, but rather temperance observed among the nobles which led to this summit of majesty. The populace was restrained by no laws – the mere whims of princes served in their place. It was the custom to guard the borders of one’s empire rather than to extend them, and one’s kingdom ended within the limits of one’s own country. Ninus, the king of the Assyrians, was the first who, from his novel desire for power, changed this ancient and as it were ancestral custom. He was the first to bring war to his neighbors, and he totally subdued the borderlands, still unable to resist the incursions of other people, all the way to Libya.
There were, to be sure, other more ancient kings like Sesostris of Egypt and Tanaus of Scythia, one of whom progressed to Pontus, and the other to the limits of Egypt. But they were pursuing distant wars, not border conflicts; they were not seeking power for themselves, but glory for their people; and in their restrained victory, they abstained from the temptations of empire. Ninus confirmed the magnitude of the dominion he earned by continued possession. His neighbors having been subdued, when he was strengthened by the accession of new powers to march to other lands and found that each victory became the instrument of the subsequent win, he subjugated all of the peoples of the east. Finally, he had a war with Zoroaster, the king of the Bactrians, who is said to have first discovered the magic arts and to have most diligently observed the origins of the world and the motions of the stars. Once Zoroaster was killed, Ninus too died, leaving behind his still young son Ninyas and his wife Semiramis.
Principio rerum gentium nationumque imperium penes reges erat, quod ad fastigium huius maiestatis non ambitio popularis, sed spectata inter bonos moderatio provehebat. Populus nullis legibus tenebatur, arbitria principum pro legibus erant. Fines imperii tueri magis quam proferre mos erat; intra suam cuique patriam regna finiebantur. Primus omnium Ninus, rex Assyriorum, veterem et quasi avitum gentibus morem nova imperii cupiditate mutavit. Hic primus intulit bella finitimis et rudes adhuc ad resistendum populos terminos usque Libyae perdomuit. Fuere quidem temporibus antiquiores Vezosis [Sesostris] Aegyptius et Scythiae rex Tanaus, quorum alter in Pontum, alter usque Aegyptum excessit. Sed longinqua, non finitima bella gerebant nec imperium sibi, sed populis suis gloriam quaerebant continentique victoria imperio abstinebant. Ninus magnitudinem quaesitae dominationis continua possessione firmavit. Domitis igitur proximis, cum accessione virium fortior ad alios transiret et proxima quaeque victoria instrumentum sequentis esset, totius Orientis populos subegit. Postremum bellum illi fuit cum Zoroastre, rege Bactrianorum, qui primus dicitur artes magicas invenisse et mundi principia siderumque motus diligentissime spectasse. Hoc occiso et ipse decessit, relicto adhuc impubere filio Ninia et uxore Semiramide.