Religion
My interest was piqued recently by how much work exists from Robert E. Howard regarding faith and the Gods of Zingara, that most melting-pot of nations. It turns out: not much.
Many pastiche writers have linked Mitra to Zingara explicitly, and while there is a good amount of logic behind that, it is never made explicit in Howard's own work. Some have gone further, placing Mitra at the head of a full Zingaran pantheon. Howard's own intentions regarding Mitra are somewhat contradictory, and one can imagine these later writers drawing parallels between Mitra and real-world figures such as Zeus, a chief deity presiding over lesser gods. Howard, however, presents Mitra as a god worshipped across a broadly polytheistic world, not as the head of any structured pantheon.
One could argue that the idea of a pantheon might have bled into Zingaran culture through its ancestral ties to Shem and eastern mythos, but this seems unlikely given the violent and turbulent nature of the events Zingara has been embroiled in throughout its history.
There is only one instance in the entire body of original REH stories where a Zingaran invokes a god's name, and notably, in that single passage, two gods are invoked: Mitra and Ishtar. This makes considerable sense when you consider that Mitra is the primary faith of Aquilonia and Poitain, while Ishtar is a Shemite deity. As Howard himself wrote in The Hyborian Age, Zingara is a nation born of mixed blood:
"Next to the Picts, in the broad valley of Zingg, protected by great mountains, a nameless band of primitives, tentatively classified as akin to the Shemites, has evolved an advanced agricultural system and existence."
"To the southwest, a tribe of Picts have invaded the fertile valley of Zingg, conquered the agricultural people there, and settled among them. This mixed race was in turn conquered later by a roving tribe of Hybori, and from these mingled elements came the kingdom of Zingara."
"Zamora lies to the east, and Zingara to the southwest of these kingdoms — people alike in darkness of complexion and exotic habits, but otherwise unrelated."
"Their marches extend from the Border Kingdom in the north to Zingara in the southwest, forming a bulwark for Aquilonia against both the Cimmerians and the Picts."
"Wishing to extend their empire, her kings made war on their neighbors. Zingara, Argos and Ophir were annexed outright."
From this we can extrapolate that the gods Zingarans worship might reflect that same mixed heritage, defined by direct ancestry or region. Add to this that Zingara is a maritime nation, where religious pressure from foreign travellers and traders would be considerable. Mitra's presence may be more dominant in certain regions owing to Zingara's period of subjugation under Aquilonia, but after breaking free there was little central authority to enforce law, let alone a national religion.
This political fragmentation is well illustrated in The Hour of the Dragon:
"Then let us unite Zingara with Poitain,' argued Trocero. 'Half a dozen princes strive against each other, and the country is torn asunder by civil wars. We will conquer it, province by province, and add it to your dominions. Then with the aid of the Zingarans we will conquer Argos and Ophir. We will build an empire—'"
Nowhere in Howard's original work is it stated or even insinuated that Zingara follows a structured pantheon. One can see how later writers might arrive at that conclusion given the nation's mixed ancestry, but the combination of Mitra's broad western dominance and Zingara's chronic lack of central authority makes the idea of an organised, doctrine-driven pantheon far-fetched.
What is well supported is that many gods are sworn by in Zingara, and that individual faith is very much a personal matter. This is perhaps best illustrated by the only line in all of Howard's Conan stories featuring a named Zingaran swearing by two gods of two different races in the same breath:
"You rogues of the Free Companies always know tricks to make men talk. I have a prisoner — the last merchant I caught, by Mitra, and the only one I've seen for a week — and the knave is stubborn. He has an iron box, the secret of which defies us, and I've been unable to persuade him to open it. By Ishtar, I thought I knew all the modes of persuasion there are, but perhaps you, as a veteran Free Companion, know some that I do not. At any rate come with me and see what you may do." — Valbroso, Zingaran border lord turned bandit chief, The Hour of the Dragon
If you are creating a Zingaran character, faith is relatively open to you, but it should remain grounded in the established gods of the Hyborian world. The most coherent approach is to lean into one of the ancestral lines running through Zingara's blood and choose accordingly. That said, Mitra and Ishtar carry the strongest canonical weight as the most likely dominant faiths in Zingara, and both have Howard's own pen behind them.