How can I affect a custom block to a custom page/view in Drupal 8? I know I can choose the page were the block Will be displayed but for a big website I Will have hundred block on same région on same admin menu, it Will be hard to handle this. Is there a way to separate the custom block or create a new space for région, because if I place a custom block in a region, this custom block Will be automatically display on all page , ans I dont want that.

Thanks.

( for drupal 8 )
Of course that you can restrict on which pages you want to show block. When you edit block you can select specific pages where block will show up.
But if you want more control you should consider to use Panels module. I recommend you to check that module and see if that will help you.