The thylacine (/ alsin / THY-l-seen, or / alsan / THY-l-syne, also / alsn /; Thylacinus cynocephalus) was the largest known carnivorous marsupial of modern times. It is commonly known as the Tasmanian tiger (because of its striped lower back) or the Tasmanian wolf (because of its canid-like appearance, traits and attributes). Native to continental Australia, Tasmania, and New Guinea, it is believed to have become extinct in the 20th century. It was the last extant member of its family, Thylacinidae; specimens of other members of the family have been found in the fossil record dating back to the late Oligocene.

Answer this question: when did the last tasmanian tiger go extinct? Let's give stream of consciousness first:
To answer the above question, the relevant sentence is: Native to continental Australia, Tasmania, and New Guinea, it is believed to have become extinct in the 20th century.
So, the final answer is the 20th century.