furthermore , each tribe will consider carefully the disposal of the eggs of their own dragon-ancestors , common tribal property , which may be used to reincarnate one of their own , should there be one of sufficient standing to merit the honor , or , far more commonly , traded to a remote tribe in more urgent need , through a complex network of communications sure to bring the news of a suitable egg to those seeking the same , this network serving to knit together tribes that might otherwise have grown more distinct , left to act in isolation .