Complex sentence: From the 1920s through much of the 20th century cigar bands tended to become more utilitarian, owing to the spread of low cost four-color printing and the growth of cigarettes, which dramatically reduced the number of cigar manufacturers and their need for brand differentiation.
Split into simpler sentences: From the 1920s onward, cigar bands have tended to become less artistically appealing and more utilitarian, owing to the spread of low cost four-color printing. In tandem with this change, the growth of the use of cigarettes dramatically reduced the number of cigar manufacturers thereby lessening their need for brand differentiation.