Thank you for submitting your item for appraisal. This appears to be a japanese watercolour depicting japanese peasants at dusk, signed lower right "shumin".
The artist is not known, possibly working as a commercial artist who produced decorative paintings for home decor in the 1930s.
The painting was obviously framed in Shanghai. The estimate is based on similar paintings offered or sold at auction. "Asking prices" in the trade can be higher and vary.