The main source for Othello was the novella called the Hecatommithi, written in 1565 by the Italian author, Cinthio. A minor source was Leo Africanus’ A Geographical History of Africa. The following is from the translation by John Pory in 1600:
The commendable actions and vertues of the Africans
The Arabians which inhabite in Barbarie or vpon the coast of the Mediterran sea, are greatly addicted vnto the studie of good artes and sciences: and those things which concerne their law and religion are esteemed by them in the first place. Moreouer they haue beene heretofore most studious of the Mathematiques, of Philosophie, and of Astrologie: but these artes (as it is aforesaid) were fower hundred yeeres agoe, vtterly destroyed and taken away by the chiefe professours of their lawe. The inhabitants of the cities doe most religiously obserue and reuerence those things which appertaine vnto their religion: yea they honour those doctours and priests, of whom they learne their law, as if they were petie-gods. Their Churches they frequent verie diligently, to the ende they may repeat certaine prescript and formal prayers; most superstitiously perswading theselues that the same day wherein they make their praiers, it is not lawfull for them to wash certaine of their members, when as at other times they will wash their whole bodies. Whereof we will (by Gods helpe) discourse more at large in the second Booke of this present treatise, when we shall fall into the mentioning of Mahumet and his religion. Moreouer those which inhabite Barbarie are of great cunning & dexteritie for building & for mathematicall inuentions, which a man may easily coniecture by their artificiall workes. Most honest people they are, and destitute of all fraud and guile; not onely imbracing all simplicitie and truth, but also practising the same throughout the whole course of their liues: albeit certaine Latine authors, which haue written of the same regions, are farre otherwise of opinion.
Likewise they are most strong and valiant people, especially those which dwell vpon the mountaines. They keepe their couenant most faithfully; insomuch that they had rather die than breake promise. No nation in the world is so subiect vnto iealousie; for they will rather leese their lives, then put vp any disgrace in the behalfe of their women. So desirous they are of riches and honour, that therein no other people can goe beyonde them. The truell in a manner ouer the whole world to exercise traffique. For they are continually to bee seene in AEgypt, in Aethiopia, in Arabia, Persia, India, and Turkie: and whithersoeuer the goe, they are most honorably esteemed of: for none of them will possesse any arte, vnlesse he hath attained vnto great exactness and perfection therein. They haue alwaies beene much delighted with all kinde of ciuilitie and modest behauiour: and it is accounted heinous among them for any man to vtter in companie, any bawdie or vnseemely worde. The haue alwaies in minde this sentence of a draue author; Giue place to thy superior. If any youth in presence of his father, his vncle, or any other of his kinred, doth sing or talke ought of loue matters, he is deemed to bee woorthie of grieuous punishment. Whasoeuer lad or youth there lighteth by chaunce into any company which discourseth of loue, no sooner heareth nor vnderstandeth what their talke tendeth vnto, but immediately he withdraweth himselfe from among them. These are the things which we thought most woortie of relation as concerning the ciuilitie, humanitie, and vpright dealing of the Barbarians: let vs now proceede vnto the residue.
Those Arabians which dwell in tents, that is to say, which bring vp cattell, are of a more liverall and ciuill disposition: to wit, they are in their kinde as deuout, valiant, patient, courteous, hospitall, and as honest in life and conuersation as any other people. They be most fairthfull obseruers of their word and promise; insomuch that the people, which before we said to dwell in the mountaines, are greatly stirred vp with emulation of their vertues. Howbeit the said mountainers, both for learning, for vertue, and for religion, are thought much inferiour to the Numidians, albeit they haue little or no knowledge at all in naturall philosophie. They are valiant, and exceeding louers and practisers of all humanitie. Also, the Moores and Arabians inhabiting Libya are somewhat ciuill of behauiour, being plaine dealers, voide of dissimulation, fauourable to strangers, and louers of simplicitie. Those which we before named white, or tawney Moores, are stedfast in friendship: as likewise they indifferently and fauourable esteeme of other nations: and wholy indeuour themselues in this one thing, namely, that they may leade a most pleasant and iocund life. Moreouer they maintaine most learned professours of liberall artes, and such men are most deuout in their religion. Neither is there any people in all Africa that lead a more happie and honorable life. What vices the foresaid Africans are subiect vnto. Neuer was there any people or nation so perfectly endued with vertue, but that they had their contrarie faults and blemishes: now therefore let vs consider, whether the vices of the Africas do surpasse their vertues & good parts. Those which we named the inhabitants of the cities of Barbarie are somewhat needie and couetous, being also very proud and high-minded, and woonderfullly addicted vnto wrath; insomuch that (according to the prouerbe) they will deeply engraue in marble any iniurie be it neuer so small, & will in no wise blot it out of their remembrance. So rusticall they are & void of good manners, that scarcely can any stranger obtaine their familiaritie and friendship. Their wits are but meane, and they are so credulous, that they will beleeue matters impossible, which are told them. So ignorant are they of naturall philosophie, that they imagine all the effects and operations of nature to be extraordinarie and diuine. They obserue no certaine order of liuing nor of lawes. Abounding exceedingly with choler, they speake alwaies with an angrie and lowd voice. Neither shall you walke in the day-time in any of their streetes, but you shall see commonly two or three of them together by the eares. by nature they are a vile and base people, being no better accounted of by their gouernours then if they were dogs. They haue neither iudges nor lawyers, by whose wisdome and counsell they ought to be directed. They are vtterly in trades of merchandize, being destitute of bankers and money-chargers: wherefore a merchant can doe nothing among them in his absence, but is himselfe constrained to goe in person whithersoeuer his wares are carried. No people vnder heauen are more addicted vnto couetise the this nation: neither is there (I thinke) to bee found among them one of an hundred, who for courtesie, humanitie, or deuotions sake will vouchsafe any entertainment vpon a stranger. Mindfull they haue alwaies beene of iniuries, but most forgetfull of benefites.
Their mindes are perpetually possessed with vexation and strife, so that they will seldome or neuer shew themselues tractable to any man; the cause whereof is supposed to be; for that they are so greedily addicted vnto their filthie lucre, that they veuer could attaine vnto any kinde of ciuilitie of good behauiour. The shepherds of that region liue a miserable, toilsome, wretched and beggarly life: they are a rude people, and (as a man may say) borne and bred to theft, deceit, and brutish manners. Their yoong men may goe a wooing to diuers maides, till such time as they haue sped of a wife. Yea, the father of the maide most friendly welcommeth her suiter: so that I thinke scarce any noble or gentleman among them can chuse a virgine for his spouse: albeit, so soone as any woman is married, she is quite forsaken of all her suiters; who then seeke out other new paramours for their liking. Concerning their religion, the greater part of these people are neither Mahumetans, Iewes, nor Christians; and hardly shall you finde so much as a sparke of pietie in any of them. They haue no churches at all, nor any kinde of prayers, but being vtterly estranged from all godly deution, they leade a sauage and beastly life: and if any man chanceth to be of a better disposition (because they haue no law-giuers nor teachers among them) he is constrained to follow the example of other mens liues & maners. All the Numidians being most ignorant of naturall, domesticall, & commonwealth-matters, are principally addicted vnto treason, trecherie, murther, theft, and robberie. This nation, because it is most slauish, will right gladly accept of any seruice among the Barbarians, be it neuer so vile or contemptible. For some will take vpon them to be dung-farmers, others to be scullians, some others to bee ostlers, and such like seruile occupations. Likewise the inhabitants of Libya liue a brutish kinde of life; who neglecting all kindes of good artes and sciences, doe wholy apply their mindes vnto theft and violence. Neuer as yet had they any religion, any lawes, or any good forme of liuing; but alwaies had, and euer will haue a most miserable and distressed life. There cannot any trechery or villanie be ijuented so damnable, which for lucres sake they dare not attempt. They spend all their daies either in most lewd practises, or in hunting, or else in warfare: neither weare they any shooes nor garments. The Negroes likewise leade a beastly kinde of life, being vtterly destitute of the vse of reason, of desteritie of wit, and of all artes. yea they so behaue themselues, as if they had continually liued in a forrest among wilde beasts. They haue great swarmes of harlots among them; whereupon a man may easily coniecture their manner of liuing; except their conuersation perhaps be somewhat more tolerable, who dwell in the principall townes and cities: for it is like that they are somewhat more addicted to ciuilitie.
Africanus, Leo. A Geographical History of Africa (Trans. John Pory. 1600).
Another minor source Shakespeare could have used is Pliny the Elder’s Naturalis Historia (original Latin), translated in 1601 by Philemon Holland. Othello’s descriptions of his conquests in Act 1, scene 3 may have come from Pliny’s work.