Jakub Sienieński was a Polish nobleman, representative in the Sejm

Sejm

The Sejm is the lower house of the Polish parliament. The Sejm is made up of 460 deputies, or Poseł in Polish . It is elected by universal ballot and is presided over by a speaker called the Marshal of the Sejm ....

, who in 1602 founded the Racovian Academy

Racovian Academy

The Racovian Academy was a school of the Socinian Polish Brethren operating in Raków, Kielce County, Poland 1602-1638, and publisher of the Racovian Catechism in 1605....

.

His father Jan Sienieński (d.1599) founded the town of Raków, Kielce County in 1569. The family name, also written "z Sienny", is not of Italian descent (from Sienna

Sienna

Sienna is a form of limonite clay most famous in the production of oil paint pigments. Its yellow-brown colour comes from ferric oxides contained within...

) but from Oleśnica

Olesnica

Oleśnica is a town in the Trzebnickie Hills in southwestern Poland with 36,951 inhabitants . It is situated in Lower Silesian Voivodeship...

.

In 1606-1609 Jakub supported the Zebrzydowski Rebellion against King Sigismund III Vasa

Sigismund III Vasa

Sigismund III Vasa was King of Poland and Grand Duke of Lithuania, a monarch of the united Polish–Lithuanian Commonwealth from 1587 to 1632, and King of Sweden from 1592 until he was deposed in 1599...

 who was attempting to weaken the Sejm

Sejm

The Sejm is the lower house of the Polish parliament. The Sejm is made up of 460 deputies, or Poseł in Polish . It is elected by universal ballot and is presided over by a speaker called the Marshal of the Sejm ....

and introduce a hereditary monarchy.