Is preemption permissible for land sold more than 50 years ago without the knowledge of the remaining heirs?

The madhhab (school of thought) of the majority of scholars is that pre-emption (shufa'ah) is not obligatory for a neighbor or a partner after division. The preponderant opinion is the affirmation of pre-emption for neighborhood when there is a shared right among the property rights, such as a road or water. If there is no shared right, then there is no pre-emption. According to the majority, pre-emption must be exercised immediately. So, if the neighbor became aware of the sale and delayed, his right is forfeited. The mentioned period (more than fifty years) makes it unlikely that it would pass without knowledge. However, if the pre-emptor was unaware of the sale, his right to pre-emption remains, even after many years.