The Ã sir and Vanir were shown as near the same age as each other . A second clan of gods , the Vanir , is also mentioned in Norse mythology : the god Njord and his children , Freyr and Freyja , are the most prominent Vanir gods who join the Ã sir as hostages after a war between Ã sir and Vanir . The Vanir appear to have mainly been connected with cultivation and fertility and the Ã sir were connected with power and war .