Okay, the user wants me to translate "river city" into Thai. Let me check the rules again. The first rule says to translate all content into Thai. The second rule states that if the content is already in Thai, leave it as is. The third rule is to provide only the translation without any explanations.
So, "river city" is in English, so I need to translate it. The direct translation would be "เมืองแม่น้ำ" because "river" is "แม่น้ำ" and "city" is "เมือง". I should make sure there's no existing Thai term that's more commonly used. Sometimes places have specific names, but since it's a general term, "เมืองแม่น้ำ" seems correct. I'll output just that without any extra text.