Complex sentence: Like hieroglyphs, hieratic was used in sacred and religious texts; also mummy labels, tomb doorjamb graffitos, ostracons, etc.; by the 1st millennium BC, calligraphic hieratic became the script predominantly used in funerary papyri and temple rolls.
Split into simpler sentences: Like hieroglyphs, hieratic was used in sacred and religious texts. By the 1st millennium BC, calligraphic hieratic became the script predominantly used in funerary papyri and temple rolls.