You should always provide more context. The short answer, is "you could, but almost certainly don't mean to." I believe you mean to say "It is called the land of watches." You could also use the contraction "It's" instead of "It is." The word "is" (from "to be") is necessary to form the passive voice. The meaning is similar to "People call it the land of watches." In theory, you could use the active voice where "it" is performing the action, ie. making the call.. however, "it" normally refers to an inanimate object, incapable of initiating a call, and "land" is also an inanimate object, incapable of receiving calls. The sentence without "is" may be grammatically possible, but doesn't make sense in the real world.

But I found the examples on the Internet: Instead, the White House has stated what it called its principles for achieving that goal. The group criticized what it called a "violent and dangerous" seizure of the vessel. It called in Saudi Arabia and other regional troops to help end the protests last month. Are there differences between British English and American English about this?

I don't think so. Both should be in the passive voice "It's called... " "It's named...." Maybe you could tell me what "it" refers to, but I can't think of a common scenario where those sentences would both make sense in the real world.

I know It is called the land of watches is passive voice.But what we learn is "It called=It named."