The world's longest freight-carrying railway line connects the Chinese city of Yiwu with Spain's Madrid. It's a much-needed link between the globe's largest wholesale market for small consumer goods, and Europe's commodity center. Now, more than four years since its first train, the line has helped boost economic cooperation and cultural exchanges.

Yiwu, China's mega wholesale center, is growing globally- Some 70 thousand small merchants in this international market sell "Made in Yiwu" goods to over 200 countries and regions, with the Belt and Road logistic system spanning in all directions.

For Yu Lingli and her handmade Chinese dolls, it boosts sales and cuts costs.

YU LINGLI YIWU MERCHANT "We sell products to many countries around the world. The freight train is very safe for cargo. It has shortened the transit time and sped up capital turnover. One of my customers says it relieves cash flow pressure and brings big savings for delivery."

At Yiwu Railway Station, small commodities and other cargo clear customs and inspection before travelling to overseas markets along the silk route railway.

This freight railway between China and Spain opened in 2014.

Since then, trains have made over 500 trips in both directions, carrying some 45,000 containers.

Its journeys in the first half of 2018 were double compared to the same period last year.

The line takes only one-third the travel time of shipping by sea and costs one-fifth that of air freight.

MAO WENJIN YIWU TO SPAIN FOUNDATION "The timeline of the train has been greatly shortened. Services have been improved and the coordination has also been greatly enhanced."

There are currently two trains a week linking the two nations.

The tracks wind through nine countries before arriving in Spain.

Some in Spain say the Yiwu-Madrid Railway is bringing enormous benefits to their country.

MAITE DIEZ PARTNER, BAKER & MCKENZIE MADRID S.L.P. "There is no question that there are a lot of economic benefits. On the one hand, with respect to exports, Spain can benefit from the growing demand from Chinese consumers for European products for quality. And in fact Spain has been exporting large amounts of meat, olive oil and wine and other food and beverage products so it will represent a big opportunity for Spanish companies to use this transport to China."

The total import and export value directly generated by the railway line has reached more than 3.5 billion US dollars.

Operators hope the service becomes even faster and brings more benefits in the future.

MAO WENJIN YIWU TO SPAIN FOUNDATION "I am convinced that the Yiwu-Madrid railway line will have a very good future. Because we are making great efforts to provide greater services. We're trying to speed up the trip and provide services that are more comprehensive to the customers."

The tracks follow the ancient silk route, proving that what's old is new, and great ideas never go out of style.