Tarai (or Terai) is the name for the southern lowlands of Nepal.
Eastern Tarai - the eastern side of the mountain range
Western Tarai - the western side of the mountain range
This article is on an extra-hierarchical region, describing a region that does not fit into the hierarchy Wikivoyage uses to organise most articles. These "extraregion" articles usually provide only basic information and links to articles in the hierarchy. This article can be expanded if the information is specific to the page; otherwise new text should generally go in the appropriate region or city article.
This website uses the Wikivoyage API to get and display all the information you see. This is the MediaWiki API, which is a general API for accessing data from Wikimedia projects. You can find information about it here: MediaWiki API.