Loosely, glass like this is referred to as Bohemian glass - your decanters were made in eastern Europe in the late 19th or possibly even early 20th century.
Decorative glass like these decanters was produced in huge quantities to satisfy the curiosity and desire of glass objects during this time. Thanks to mass production methods, suddenly fancy glass was something everyone could afford to have in their home.
I guess you can see where this is going value-wise...such objects remain common today and do not command a whole lot of value.