Relationships, and not just business ones, are important in any culture and even more so in the deeply interconnected culture of Japan. It is necessary not only to establish and develop relationships, but also to understand the context of why and with whom you are building relationships. On the other hand, you also have to be careful not to establish certain relationships at all or to end them as soon as possible. Generally, this network of mutual business ties is called keiretsu in Japanese. Keiretsu refers to a group of enterprises that are interconnected in business terms, including share ownership. There are two types of keiretsu: horizontal keiretsu - in Japanese kigyo shudan (diverse business groups centred around a bank and its trading company - e.g. Mitsui keiretsu) and vertical keiretsu, called seisan keiretsu (production) and ryutsu keiretsu (distribution). That is, production of a particular product - e.g. Toyota and its network of distributors. The keiretsu network was highly interdependent and largely self-sufficient until the 1990s.