The link, first established late last year, is part of the Chinese government’s plans to create a "21st century Silk Road" and boost trade with both Central Asia and Europe.

　　The first direct freight train from China to Madrid carrying Christmas paraphernalia arrived in December.

　　It returned laden with wine and olive oil, in time for the Chinese New Year in February.

　　世上最长铁路促进中欧贸易

　　Since then, there have been three more round trips from Yiwu to Madrid.

　　The journey, spanning over 8-thousand miles cuts across eight different countries, which has created logistical issues, as the cargo has to be moved on to different trains three different times along the route because of incompatible rail gauges in different countries.

　　Still, Analyist Mario Esteban with the Elcano Royal Institute, a Spanish think-tank, says sending material along the line still poses fewer security risks than using sea routes.

　　"Most of the trade between China and Europe goes by the sea because is cheaper, even though it takes a bit more of time. What's the problem? This long sea route passes by very sensitive strategic areas, such as strait of Malacca or the Gulf of Aden."

　　Another issue is cost.

　　Sending goods on the route costs around 5-thousand US dollars per container, which is more expensive than shipping by sea.

　　Still, Zhang Ruizhi, a top manager at a Chinese Import-Export firm, says sending non-perishables by train still makes economic sense.

　　"The time it takes to ship is much faster than traditional sea shipping. The train takes approximately 18-21 days. Compared with sea shipping, it's about twice the speed of shipping by sea. Although it's longer than air transport, but the cost of shipping by train is far more economical. As a result we chose to import our goods by train."

　　It is also more environmentally friendly than road transport, which would produce 114 tonnes of CO2 to shift the same volume of goods, compared with the 44 tonnes produced by the train – a 62% reduction according to analysts.

　　The rail link connecting China to Spain is one of several rail connections between China and Europe.

　　Another route runs between Chongqing and the German trading hub of Duisburg five times a week.

　　There is also a rail link between Beijing and Germany's second largest city, Hamburg, which has cut down transportation times to just 20 days.

　　China is the European Union's biggest source for imports, and is China's largest trading partner.

　　The Chinese government plans to invest billions of dollars more in the future through the Asian Infrastructure Investment Bank to create more infrastructure projects through Central Asia.

　　For Cri I'm Poornima Weerasekara.