Short answers, pulled from the story.
King Edward I of England created a national customs collection system in 1275. This administrative structure turned tax evasion into a recognized crime for the first time in recorded history.
The system targeted exports like wool and hides which carried high taxes under royal decree. Merchants quickly found ways to move these goods without paying the state its due share using hidden transport methods or misdescribed cargo on paper.
High rates of duty levied on tea, wine, spirits, and luxury goods made clandestine import highly profitable for impoverished fishermen and seafarers. In places like Romney Marsh, East Kent, Cornwall, and East Cleveland, smuggling became more economically significant than legal farming or fishing.
A U.S. government report published in 2003 estimates that 800,000 to 900,000 people worldwide are trafficked across borders each year. Criminal organizations choose human cargo because people can be used repeatedly and require little capital investment compared to other commodities.
Smugglers use dogs to strap drugs onto their backs and cats to sneak drugs into prisons where gangs sell them to inmates. Livestock like cattle, goats, sheep, llamas, elephants, and camels serve as living body couriers or pack animals depending on regional availability.