Although the Tang dynasty had military clashes with the Islamic empire (Caliphate) at the west front such as the Battle of Talas or negotiations including trade, its notion of Tenka, unlike that of the Qin and Han empires, did not include the nations which stood on an equal footing with it, such as Xiongnu.
タラス河畔の戦いに代表されるように、西方で匹敵するイスラーム帝国と軍事的衝突や交易など交渉があったが、唐朝はかつての秦漢帝国と異なり、その天下概念には匈奴のような対等国は基本的には存在しなかった。