I have several excellent links on my Teacher’s Page that provide resources to teachers preparing history lessons that would be accessible to English Language Learners.
One section is, for obvious reasons, focused just on California resources. One of several sites in this category is Calisphere, a relatively new collection developed by the University of California.
The other section, called Social Studies Resources, provides broader history links. These include sites that offer some decent lesson plans and hand-outs, such as Family Education and History World.