I believe you mean you have a gun with the Brazilian star with a 1937 date beneath it. That serial number probably was first marked on a frame manufactured in the early 1920s. These guns were never made up until after WWII, when S&W got a second order from Brazil (the first one was in 1937) for several thousand Model 1917s in .45 ACP. Those postwar guns were made up from '20s-era parts, and were shipped to Brazil in 1946. But they have the Brazilian stamp with the 1937 date.
Thus there are two answers to your question. The frame was probably manufactured and numbered around 1920-22; then it was in storage for more than two decades, and S&W built it into a gun that was shipped to Brazil under terms of the second Brazilian contract in 1946.