Complex sentence: The Luciano-Costello-Lansky alliance prospered even further with the passage of Prohibition in 1920, the gang went into bootlegging, financed by criminal financier Arnold Rothstein.
Split into simpler sentences: The Luciano-Costello-Lansky alliance prospered even further with the passage of Prohibition in 1920. The gang went into bootlegging, financed by criminal financier Arnold Rothstein.