documentclass[a4paper, twoside]{book}

usepackage{polyglossia}
newfontfamily{greekfont}{Calibri}[
  Script=Greek,
  NFSSFamily=liberationserif,
]
newfontfamily{greekfontsf}{Calibri}[
  Script=Greek,
  NFSSFamily=liberationsans,
]
newfontfamilyarabicfont[Script=Arabic]{Amiri}%
newfontfamilyarabicfonttt[Script=Arabic,Scale=.75]{DejaVu Sans Mono}
newfontfamilyfarsifont[Script=Arabic,Scale=1.1,WordSpace=2]{Adobe Arabic}
newfontfamilymySymbolsFont{Segoe UI Symbol}
setdefaultlanguage[spelling=new]{german}
setotherlanguage[variant=ancient]{greek}

setotherlanguage[numerals=western]{arabic}
setotherlanguage{farsi}

usepackage{longtable}

begin{document}

chapter{Deutsch}

content does not matter

end{document}

setotherlanguage[numerals=western]{arabic}
setotherlanguage{farsi}