2005 or 2006 Threads???

Hi

While searching for the old threads I could not find the threads that have been created in the years 2006 or 2005. SDN is only allowing to search from 2007 year.... Where are all the

threads of years 2005 and 2006 have gone?? Are they archived? if yes, can any one please let me know where I can find 2005 or 2006 Threads?

Thank you in advance