Arnold Rothstein was def a key figure in modern organized crime and he died at the age of 46.

Jewish gangs were very big during Prohibition--generally much bigger than Italian gangs--and dominated the booze trade in most big cities. But, many Prohibition-era Jewish gangsters went legit after Repeal, and focused on gambling. They often worked with Mafia families but were never part of them,

Individual Jewish gangsters sometimes advised Mafia families. Lansky was very close to Luciano, Costello and Adonis, often partnering with them. Jack Guzik was Capone's close friend, advisor and mentor when he was new in Chicago. Rothstein gathered a cadre of up-and-coming Italian gangsters around him in the early '20's--including Luciano and Costello (also Lansky and Siegel), advised them and gave them political protection. But, he was killed in '28. Longy Zwillman was the OC leader of northern NJ and often was a senior partner to Boiardo and Catena. Moe Dalitz was "Mr. Las Vegas" and probably helped Mafia guys.

Overall: They often cooperated with Mafia families, and some Jewish individuals advised powerful Mafiosi, but they weren't always, or even often, the financial guiding lights of the Mafia.

Yeah we all know Maranzano wasn’t jewish.
But its still a name that don’t get recognize.

For the jewish question, I think Cosa Nostra took everything that work of every crime organization that were successful and made it there own.

They took the organization and buisness asset from the jewish mob.
The contacts in the political world from the irish mob and probably the syndicate world.
The gambling operations from the african-american mob.
And I guess many other things from all type of criminal world.

The thing is that the italians succeed to make all of this an organization that work like an entreprise, and still being a criminal thing.

He wasn't Jewish. but Murray Humphries was also wildly impactful figure on LCN.

Yes The Hump was an important fixer.

Sidney Roy Korshak also read Supermob interesting stuff about Chicago's Jews in the upper echelons of power as well as the Chicago Outfit.

I definitely agree with you on certain things Turnbull. But def disagree on a few others.

I do agree that Jewish gangs were extremely prominent during the Prohibition era, as were Irish gangs and Italians also. And depending upon which particular city you're speaking of, some Jewish mobs where even more dominant for awhile. Playing a role as significant leaders, or firsts among equals, in alcohol-bootlegging and several other rackets. In the garment district, Lepke Buchalter and his mob dominated that industry. He was also very prominent in other forms of "industrial racketeering." He was a powerhouse.

But the Jewish gangs were never, "generally much bigger than Italian gangs," as you mentioned, nor did they dominate cities like NYC and Chicago (to name just two).

If taken in their totality; the Napolitani (Camorra), Calabrese (Societa' Onorata), and Siciiani (Mafia), collectively, dwarfed any one particular ethnicity in underworld power. Even back then. But during the 1910s-1920s, even into the 1930s, these Italian "Mafias" were separate entities. And for the most part, operated in the shadows. Away from the limelight. It was only after their amalgamation, after the Commission was formed in 1931, and these three "Mafias" became one group, that America (and even the underworld) later started to realize the totality of their collective power.

And dating back to the 1920s-1930s, yes, in general, the various "ethnic" gangs were mostly independent, but sometimes worked with one another too. And once again, depending upon the city discussed, Italians and Jewish gangs interacted to a greater or lesser degree. Fellas like Longy Zwillman as you mentioned, Dutch Schultz, Lepke Buchalter, etc., all headed their own gangs. And yes, each of these organizations were very large and powerful in their own right. And "independent" of Cosa Nostra (for the time being)...

But by the mid-late 1940s, and certainly into the early 1950s, most Jewish gangs had either faded away, or been absorbed and amalgamated into Cosa Nostra as formal "associates" of the various "Families" across the United States. On the East Coast for sure. Meyer Lansky (and by extension), his large cadre of Jewish associates, for sure. They were considered "on record" associates of the Luciano/Genovese Family.

I suspect the same held true for most top Jewish mobsters in various major cities throughout the U.S.
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As far as certain Jewish mob figures "advising" Cosa Nostra? In some situations that was the case. Again, Meyer Lansky is a perfect example that. For decades, he was a pivotal figure within Lucky Luciano's Family. Considered a "top" associate. Lansky was a sharp guy. Very sharp! So naturally, Luciano, who was no fool himself, entertained many of Lansky's financial ideas. History shows he trusted Lansky immensely.

As you pointed out, that doesn't mean guys like Meyer Lansky was the Mafia's "guiding light," but they did, in fact, sometimes advise them on good business investments and in illicit rackets, and partner with mafiosi.

But Lansky, was not, as some others over the years have falsely claimed, the Luciano Family's "consigliere," or the Mafia's "financial accountant." IMO, those types of titles do not present Lansky in a proper light.
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As far as Jewish mob figures later abandoning illegal rackets for "legalized gambling" in Las Vegas and elsewhere, that was sometimes the case. Cleveland's Jewish Mob is a perfect example of that. After the made a fortune in bootlegging, they dovetailed their success by reinvesting their profits into Nevada's gaming industry. A brilliant move (as it turned out). Others did the same.

But even in this instance, guys like Moe Dalitz and his partners brought in certain Mafia bosses, giving them a "piece of the pie," so as to have their blessing, and to have their protection.