What is one essential element of historical fiction?

The essential element of historical fiction is the presence of historical figures or events.

In some works of historical fiction, famous events appear from points of view not recorded in History, showing real historical figures dealing with events allusive to the time but at the same time, showing them in a different way than is recorded in History . At other times, the historical event complements a narrative story, which occurs in the background. At times, historical fiction may be mostly corresponding to historical reality, but the names of people and places have been somewhat altered.

they would have to clean it very clean

sentences vary by structure as well as by function. there are compound, complex, and compound-complex sentences.

simple sentence

i like to read.

a simple sentence has one independent clause.

compound sentence

i like to read, and i also like to write.

a compound sentence includes more than one independent clause, connected by a coordinating conjunction (and, but, for, nor, or, so, or yet).

complex sentence

i prefer to read books that are bestsellers.

a complex sentence includes one independent clause and one or more dependent clauses. (a dependent clause is one that cannot stand alone.) types of dependent clauses include relative clauses (i kicked the boy who pinched me), adverb clauses (i am going home now because i have a curfew), and noun clauses (i don't know what to do next).

compound-complex sentence

although i prefer to read current bestsellers, i do like to read old agatha christie mysteries, and i also like some 20th-century science fiction.

compound-complex sentences take a bunch of clauses (multiple independent clauses, and one or more dependent clauses) and toss them together like a salad. although these sentences take practice to write in a grammatically correct fashion, they can hold a tremendous amount of meaning, and are common in academic writing.