the zebrzydowski rebellion (1606–1607) marked a substantial increase in the power of the polish magnates, and the transformation of "szlachta democracy" into "magnate oligarchy". the commonwealth's political system was vulnerable to outside interference, as sejm deputies bribed by foreign powers might use their liberum veto to block attempted reforms. this sapped the commonwealth and plunged it into political paralysis and anarchy for over a century, from the mid-17th century to the end of the 18th, while its neighbors stabilized their internal affairs and increased their military might.