ContentMap is node properties exposed as a Map. What you want to iterate over are subnodes, hence it can't work.
Looking at your structure, it looks like a link list area, if that is so <cms:area name="events" />
should be enough in the component that renders area and in the area itself something like:
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core"%>
<%@ taglib prefix="cms" uri="http://magnolia-cms.com/taglib/templating-components/cms"%>
<div id="${def.parameters.divId}">
<c:forEach items="${components}" var="component">
<cms:component content="${component}" />
</c:forEach>
</div>
where components
should be exposed implicitly in the area. Try to get magnolia-templating-samples module from git/nexus for more examples like that.
HTH, Jan