Since the Middle Ages, at least.
500 meters
A flight from Warsaw, Poland --> Hurghada, Egypt would take almost 5 hours.
9 hrs flight from nyc jfk to Warsaw
5 years
1,000 years.
3 hours and 50 minutes duration
Two and half to three hours from London based airports to Warsaw.
Since about AD1100.
This depends on your definition of country. Poland has been its own country, the Republic of Poland, since 1989.
310,000+ Jews were sent to Treblinka. The time period was between less than 3 months.
Poland has not been a monarchy for a very long time.
The short answer is: about one thousand years. See the attached Related Link.