Fortunately for Joseon, instead of invading them immediately, from late 1633 to mid 1635, Later Jin set out to conquer nearby Ming and Mongolian territories with particular attention to Chahar Mongol tribe. While this period should have been the opportunity for the Joseon government to strengthen their defense, political situations stood in their way. First, a Ming envoy, Lu Weining visited Joseon in June 1634 to preside at the installation ceremony of their crown prince. Unfortunately for Joseon, the envoy requested excessive amount of bribe in return for the ceremony. In addition, quite a few merchants who attended the envoy sought to make a huge fortune by forcing unfair trades upon their Joseon counterparts. This envoy visit eventually cost Joseon more than 100,000 taels of silver. King Injo, who had successfully accomplished installations of both his parents and son with help from Ming, now attempted to relocate the memorial tablet of his late father into the Jongmyo Shrine. As his father has never actually ruled as the king, this attempt met with severe opposition from government officials, which lasted until early 1635. Adding to this, the mausoleum of King Seonjo was accidentally damaged in March 1635 and the political debate about its responsibility continued for the next few months. These political gridlocks prohibited Joseon from taking enough measure to prepare for a possible invasion from Later Jin.
Question: How many years did Later Jin take to set out to conquer Ming and Mongolian territories?
Answer: 2