A Dar es Salaam court on Tuesday sentenced a Chinese woman dubbed the "Ivory Queen" to 15 years in prison for her role in illegal ivory trade.
Yang Fenglan, 69, was convicted for trafficking 706 elephant tusks worth $2.5 million between 2000 and 2014.
She has been sentenced alongside two Tanzanian men - Salvius Matembo and Philemon Manase.
Ms Fenglan had been charged with leading one of Africa's biggest ivory smuggling rings, responsible for the slaughter of hundreds of elephants.
"The prosecution proved the case against the accused beyond a reasonable doubt," Judge Huruma Shaidi told the court.
Wildlife campaigners have called it one of the most important cases for several years.
Ms Fenglan, who has lived in the East African nation since the 1970s, was convicted of organising a smuggling ring between Tanzania and Asia.
When she was arrested in 2015 she was vice president of the China-Africa Business Council of Tanzania.
Poaching has seen the population of African elephants fall by 110,000 over the past decade to just 415,000 animals, according to the International Union for Conservation of Nature (IUCN).
The slaughter is being fuelled especially by demand in Asia, where ivory is used for jewellery and ornamentation.