Our earliest reliable source for early Nabataean history comes from Diodorus Siculus' Bibliotheca historica. Diodorus was a Sicilian-Born Greek living in the first century BCE. He got his information on the Nabataeans from the fourth-century BCE writer, Hieronymus of Cardia, who had served under Alexander the Great's generals. The following quotation concerning the life of the early Nabataeans is from Diodorus' Bibliotheca historica, Book XIX.94.1-10.

For the sake of those who do not know, it will be useful to state in some detail the customs of those Arabs, by following which it is believed, they preserve their liberty.

They live in the open air, claiming as native land a wilderness that has neither rivers nor abundant springs from which it is possible for a hostile army to obtain water. It is their custom neither to plant grain, set out any fruit-bearing tree, use wine, nor construct any house; and if anyone is found acting contrary to this, death is his penalty. They follow this custom because they believe that those who possess these things are, in order to retain the use of them, easily compelled by the powerful to do their bidding.

Some of them raise camels, others sheep, pasturing them in the desert. While there are many Arabian tribes who use the desert as pasture the Nabataeans far surpass the others in wealth although they are not much more than ten thousand in number; for not a few of them are accustomed to bring down to the sea frankincense which they procure from those who convey them from what is called Arabia Eudaemon [Arabia Felix].

They are exceptionally fond of freedom; and whenever a strong force of enemies comes near, they take refuge in the desert, using this as a fortress; for it lacks water and cannot be crossed by others, but to them alone, since they have prepared subterranean reservoirs lined with stucco, it furnishes safety.

As the earth in some places is clayey and in others is of soft stone, they make great excavations in it, the mouths of which they make are very small, but by constantly increasing the width as they dig deeper, they finally make them of such size that each side has the length of one plethrum [about 100 ft.]. After filling these reservoirs with rain water, they close the openings, making them even with the rest of the ground, and they leave signs that are known to themselves but are unrecognizable by others. They water their cattle every other day, so that, if they flee through waterless places, they may not need a continuous supply of water.

They themselves use as food flesh and milk and those of the plants that grow from the ground which are suitable for this purpose; for among them there grow the pepper and plenty of the so-called wild honey from trees, which they drink mixed with water. . . .