It is said to be the most important anti-smuggling operation carried out by Ningbo (in the eastern province of Zhejiang) Customs Police during their investigation into wet salted hides illegal trading. Customs authorities have caught three criminal gangs (ten people have been taken under arrest, especially in the province of Zhejiang and in Shanghai), which had obviously created a seemingly legal network to import 23,000 tons of hides in the period from January 2016 to November 2017. Once raw hides were imported, smugglers could place them in illegal tanneries. Besides the national revenue loss, hides were not assayed. Hence, they were harmful in terms of health and environment.