Musse Yusuf, 32, and Ahmed Mohamed, 33, of Bow, east London, made terrorist material available to others through websites which they ran, it is claimed.
The pair are also alleged to have raised money for supporting terrorism, with substantial sums
of cash passing through bank accounts operated principally by Mohamed.
Police searches of their homes in Britain uncovered large quantities of terrorism-related material stored within computer hard drives, Kingston Crown Court heard.
Prosecutor Max Hill QC said that in the case of Yusuf the "instructional" material included terrorist manuals and videos containing information on making suicide vests, improvised explosive devices or bombs, entitled the Mujahideen Terrorist Handbook and the Mujahideen Explosives Handbook.
Opening the Crown's case, Mr Hill told the jury: "Although a long way from their country of birth, these defendants used this country as a safe base from which to encourage and facilitate criminal activity of the most serious kind, namely jihad-style terrorism.
"The allegations against the defendants are very serious crimes which are specifically covered by the laws of this country enacted by Parliament both before and after the atrocities with which we are all familiar, namely 9/11 in New York and 7/7 in London.
"Those laws prohibit the planning of terrorist activity within this country even where the intended target is within another country."
Mohamed denies dissemination of terrorist publications and fundraising contrary to the Terrorism Act between January 2006 and May last year.
Yusuf denies the same charges, as well as four counts of possession of a document or record for terrorist purpose contrary to the Terrorism Act in May last year.