Why did Yugoslavia split between 1991-1995?I need simple reasons for what happened.

The link below gives a really good and detailed account of
the reasons why Yugoslavia split.  Please consult it.

The
basic reason why Yugoslavia split is that there were too many different ethnic and
religious groups within the country.  As an example, Serbs and Croats are ethnically
somewhat different.  They write their language with different alphabets.  Most
importantly, Serbs are Orthodox Christians while Croats are Catholic.  These differences
made the groups feel different from one another.  (And there many other ethnic groups as
well...)

The differences between these ethnic groups were
not a problem during communist times because the communists kept the country under tight
control and conflict could not erupt.  Once the communists left power, however, the
various ethnic groups were free to act as they wished.  This led to conflict between the
groups and those conflicts eventually led to a horrible civil war with terrible
atrocities committed by a variety of sides.

So Yugoslavia
split because it was made up of groups that did not see themselves as similar to one
another.  Once the repressive communist government was gone, these groups came into
conflict and the country split apart.