Original: Rising in Mongolia , it follows a northerly course to the Yenisei Gulf in the Kara Sea , draining a large part of central Siberia , the longest stream following the Yenisei-Angara-Selenga-Ider .
Simplified: The river drains a large part of central Siberia , the longest stream following the Yenisei-Angara-Selenga-Ider is about 5539 km long .