I’m not going to delve too deeply into the debate here other than to note that references to as-nas don’t really turn up until the late 19th century -- that is, after poker had already established itself in North America in the early 1800s -- which obviously challenges the idea that poker borrowed from it.
Some as-nas decks date from around 1800 (just a little before poker), and a couple of writers of books about card games boldly declared it to be an early version of poker. But later on it was observed that “as” -- referring to the ace -- isn’t really a Persian word at all but a borrowing of the French word for ace, kind of strengthening the suggestion that as-nas decended from the European “vying” games we’ve been discussing.
Like I say, though, let me just set all that aside and explain quickly how to play as-nas. We call it a “Persian” card game because it wasn’t until the 1930s that the West started referring to the country of its origin as Iran (even if those living there referred to it as such well before), and the game was played well before that.
The game uses a 20-card deck for up to four players or a 25-card deck if five are playing. Players are each dealt five cards (clockwise), then a betting round follows with the rules for betting very much resembling that of poker, including allowing for a blind bet (like a “straddle”) before the cards are dealt. After the betting comes the showdown (for players still in the hand), and the highest-ranking hand wins. (That is, there’s no draw or second betting round.)
The cards used in as-nas are analogous to the A-K-Q-J-10 in poker, although they’re designated a little differently. The “as” (ace) often features a lion; the “shah” (king) has a king-like figure on a throne or horse; the “bibi” (lady) depicts a mother and child; the “serbaz” (soldier) is a soldier-figure; and the “couli” (an unnumbered card considered the lowest) is a dancing figure.
There are four suits (spades, hearts, diamonds, clubs), although suits don’t figure in the hand rankings. If five players are playing, five more cards of the same rankings -- in a fifth suit (I’m not sure what) -- are employed.
I’m seeing some differences in how hand rankings are described, although most seem to say flushes and straights don’t count, and the only hands that matter are (highest-to-lowest) four of a kind, a full house, three of a kind, two pair, one pair, and high-card, with “kickers” counting to help break ties. Obviously players can bluff, with a bluff being called a “tûp.”
This is more or less “Old Poker,” an early version of poker with a 20-card deck that also had only a single round of betting and no draw, although examples of the latter game started incorporating the larger deck as well as flushes and straights. The parallels make it easy enough to see why some want to hold up as-nas as the most direct precursor to poker, as certainly its resemblances are more extensive than is the case with any of the other European games.
But as has also been argued, that may not be such a coincidence given that the Persian game may well have come a little after poker and not before.