A compound sentence consists of two or more simple sentences, grammatically independent of one another and generally united by a coördinating conjunction. Thus,
τῇ δὲ ὑστεραίᾳ ἐπορεύοντο διὰ τοῦ πεδίου καὶ Τισσαφέρνης εἵπετο
a. Abbreviated compound sentences, i.e. sentences containing a compound subject with a single verbal predicate or a single subject with a compound verbal predicate, are treated in this book as expanded simple sentences ( cross923, cross924).
Herbert Weir Smyth [n.d.], A Greek Grammar for Colleges; Machine readable text [info] [word count] [Smyth].