Company A is a German company. Company B is an American company.
Company B has a 10 year exclusive contract with company A to market
and sell Company A?s products in the United States. Now company A
declares itself insolvent under German law and the German federal
government appoints an administrator. The administrator asks company B
(as well as other distributors around the world) to continue trading
with company A in order to generate revenue during the period of
insolvency, this company B does. Some 5 months later the assets of
company A are sold to company C.

Was the contract with company B terminated by the insolvency
proceedings, or did company B have the right to assume that the
contract was not terminated as they continued to purchase company A?s
product at the request of the administrator.

Please quote relevant German statutes, as unfortunately opinions will
not count. We will tip handsomely for a full answer with references.

These seems to be the law in question ("Insolvenzordnung", InsO):

http://bundesrecht.juris.de/bundesrecht/inso/index.html

Correcting my previous comment: "This seems to be ..."

Thank you fp-ga for your valuable comment. We will try to find a
translator. If there are any researchers who would like to pick up
this ball and run with it, we have no issues with paying for a
conclusion to fp's highly appreciated work.