What is "hasideans"

The Hasideans (Hasidæans or Assideans; , Hasidim ha-Rishonim, "ancient Pietists", Greek Ἀσιδαῖοι) were a Jewish religious party which commenced to play an important role in political life only during the time of the Maccabean wars, although it had existed for quite some time previous. They are mentioned only three times in the books of the Maccabees.