Yiwu-Madrid: la ruta de tren más larga del planeta no es el Transiberiano. This article from National Geographic (Spain) describes the longest train route in the world to date. I'm planning on using it to spark curiosity in my students as we normally think of merchandise from China being "shipped" by large vessels. We all have heard (or suffered) the quagmire of shipment delays because of the pandemic, etc. The article shows pictures and references that students can research further with regards to the use of railways for trade between Spain and China, as well as other European countries.
In addition, there's another article from Spanish.Xhinua.com that talks about diplomatic ties between China and Spain.