This is the 9689th most frequent Russian word.
чжан
The word "чжан" is not a standard Russian word; it might be a transliteration of a Chinese surname (e.g., Zhang).
Here, 'Чжан' is used as a proper noun to refer to a person's name.
Чжан - мой лучший друг, и он из Китая.
Zhang is my best friend, and he is from China.
In this context, 'чжана' (the genitive case of 'Чжан') indicates possession, specifically attributing the recipe to Zhang.
В этом ресторане подают наивкуснейшие блюда по рецепту чжана.
This restaurant serves the most delicious dishes according to Zhang's recipe.
In this sentence, 'Чжанцзяцзе' is a proper noun referring to the Zhangjiajie region, and it incorporates 'Чжан' as part of the name.